[TS/JS] Entry point per namespace and reworked 1.x compatible single file build (#7510)

* [TS/JS] Entry point per namespace

* Fix handling of outputpath and array_test

* Attempt to fix generate_code

* Fix cwd for ts in generate_code

* Attempt to fixup bazel and some docs

* Add --ts-flat-files to bazel build to get bundle

* Move to DEFAULT_FLATC_TS_ARGS

* Attempt to add esbuild

* Attempt to use npm instead

* Remove futile attempt to add esbuild

* Attempt to as bazel esbuild

* Shuffle

* Upgrade bazel deps

* Revert failed attempts to get bazel working

* Ignore flatc tests for now

* Add esbuild dependency

* `package.json` Include esbuild

* `WORKSPACE` Add fetching esbuild binary

* Update WORKSPACE

* Unfreeze Lockfile

* Update WORKSPACE

* Update BUILD.bazel

* Rework to suggest instead of running external bundler

* Add esbuild generation to test script

* Prelim bundle test

* Run test JavaScriptTest from flatbuffers 1.x

* Deps upgrade

* Clang format fix

* Revert bazel changes

* Fix newline

* Generate with type declarations

* Handle "empty" root namespace

* Adjust tests for typescript_keywords.ts

* Separate test procedure for old node resolution module output

* Fix rel path for root level re-exports

* Bazel support for esbuild-based flatc

Unfortunately, we lose typing information because the new esbuild method
of generating single files does not generate type information.

The method used here is a bit hack-ish because it relies on parsing the
console output of flatc to figure out what to do.

* Try to fix bazel build for when node isn't present on host

* Auto formatting fixes

* Fix missing generated code

Co-authored-by: Derek Bailey <derekbailey@google.com>
Co-authored-by: James Kuszmaul <jabukuszmaul+collab@gmail.com>

tests/ts/arrays_test_complex/my-game/example/array-struct.ts

@@ -0,0 +1,166 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+import * as flatbuffers from 'flatbuffers';
+
+import { NestedStruct, NestedStructT } from '../../my-game/example/nested-struct.js';
+import { OuterStruct, OuterStructT } from '../../my-game/example/outer-struct.js';
+
+
+export class ArrayStruct implements flatbuffers.IUnpackableObject<ArrayStructT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):ArrayStruct {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+aUnderscore():number {
+  return this.bb!.readFloat32(this.bb_pos);
+}
+
+bUnderscore(index: number):number|null {
+    return this.bb!.readInt32(this.bb_pos + 4 + index * 4);
+}
+
+c():number {
+  return this.bb!.readInt8(this.bb_pos + 64);
+}
+
+d(index: number, obj?:NestedStruct):NestedStruct|null {
+    return (obj || new NestedStruct()).__init(this.bb_pos + 72 + index * 1072, this.bb!);
+}
+
+e():number {
+  return this.bb!.readInt32(this.bb_pos + 2216);
+}
+
+f(index: number, obj?:OuterStruct):OuterStruct|null {
+    return (obj || new OuterStruct()).__init(this.bb_pos + 2224 + index * 208, this.bb!);
+}
+
+g(index: number):bigint|null {
+    return this.bb!.readInt64(this.bb_pos + 2640 + index * 8);
+}
+
+static getFullyQualifiedName():string {
+  return 'MyGame.Example.ArrayStruct';
+}
+
+static sizeOf():number {
+  return 2656;
+}
+
+static createArrayStruct(builder:flatbuffers.Builder, a_underscore: number, b_underscore: number[]|null, c: number, d: (any|NestedStructT)[]|null, e: number, f: (any|OuterStructT)[]|null, g: bigint[]|null):flatbuffers.Offset {
+  builder.prep(8, 2656);
+
+  for (let i = 1; i >= 0; --i) {
+    builder.writeInt64(BigInt(g?.[i] ?? 0));
+  }
+
+
+  for (let i = 1; i >= 0; --i) {
+    const item = f?.[i];
+
+    if (item instanceof OuterStructT) {
+      item.pack(builder);
+      continue;
+    }
+
+    OuterStruct.createOuterStruct(builder,
+    item?.a,
+    item?.b,
+    (item?.cUnderscore?.a ?? 0),
+    (item?.cUnderscore?.b ?? []),
+    (item?.cUnderscore?.c ?? 0),
+    (item?.cUnderscore?.dUnderscore ?? BigInt(0)),
+    item?.d,
+    (item?.e?.a ?? 0),
+    (item?.e?.b ?? []),
+    (item?.e?.c ?? 0),
+    (item?.e?.dUnderscore ?? BigInt(0)),
+    item?.f
+    );
+  }
+
+  builder.pad(4);
+  builder.writeInt32(e);
+
+  for (let i = 1; i >= 0; --i) {
+    const item = d?.[i];
+
+    if (item instanceof NestedStructT) {
+      item.pack(builder);
+      continue;
+    }
+
+    NestedStruct.createNestedStruct(builder,
+    item?.a,
+    item?.b,
+    item?.cUnderscore,
+    item?.dOuter,
+    item?.e
+    );
+  }
+
+  builder.pad(7);
+  builder.writeInt8(c);
+
+  for (let i = 14; i >= 0; --i) {
+    builder.writeInt32((b_underscore?.[i] ?? 0));
+
+  }
+
+  builder.writeFloat32(a_underscore);
+  return builder.offset();
+}
+
+
+unpack(): ArrayStructT {
+  return new ArrayStructT(
+    this.aUnderscore(),
+    this.bb!.createScalarList<number>(this.bUnderscore.bind(this), 15),
+    this.c(),
+    this.bb!.createObjList<NestedStruct, NestedStructT>(this.d.bind(this), 2),
+    this.e(),
+    this.bb!.createObjList<OuterStruct, OuterStructT>(this.f.bind(this), 2),
+    this.bb!.createScalarList<bigint>(this.g.bind(this), 2)
+  );
+}
+
+
+unpackTo(_o: ArrayStructT): void {
+  _o.aUnderscore = this.aUnderscore();
+  _o.bUnderscore = this.bb!.createScalarList<number>(this.bUnderscore.bind(this), 15);
+  _o.c = this.c();
+  _o.d = this.bb!.createObjList<NestedStruct, NestedStructT>(this.d.bind(this), 2);
+  _o.e = this.e();
+  _o.f = this.bb!.createObjList<OuterStruct, OuterStructT>(this.f.bind(this), 2);
+  _o.g = this.bb!.createScalarList<bigint>(this.g.bind(this), 2);
+}
+}
+
+export class ArrayStructT implements flatbuffers.IGeneratedObject {
+constructor(
+  public aUnderscore: number = 0.0,
+  public bUnderscore: (number)[] = [],
+  public c: number = 0,
+  public d: (NestedStructT)[] = [],
+  public e: number = 0,
+  public f: (OuterStructT)[] = [],
+  public g: (bigint)[] = []
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  return ArrayStruct.createArrayStruct(builder,
+    this.aUnderscore,
+    this.bUnderscore,
+    this.c,
+    this.d,
+    this.e,
+    this.f,
+    this.g
+  );
+}
+}