[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/table-a.ts

@@ -0,0 +1,87 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+import * as flatbuffers from 'flatbuffers';
+
+import { TableB, TableBT } from './my-game/other-name-space/table-b.js';
+
+
+export class TableA implements flatbuffers.IUnpackableObject<TableAT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):TableA {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsTableA(bb:flatbuffers.ByteBuffer, obj?:TableA):TableA {
+  return (obj || new TableA()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsTableA(bb:flatbuffers.ByteBuffer, obj?:TableA):TableA {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new TableA()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+b(obj?:TableB):TableB|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new TableB()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
+static getFullyQualifiedName():string {
+  return 'TableA';
+}
+
+static startTableA(builder:flatbuffers.Builder) {
+  builder.startObject(1);
+}
+
+static addB(builder:flatbuffers.Builder, bOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(0, bOffset, 0);
+}
+
+static endTableA(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  return offset;
+}
+
+static createTableA(builder:flatbuffers.Builder, bOffset:flatbuffers.Offset):flatbuffers.Offset {
+  TableA.startTableA(builder);
+  TableA.addB(builder, bOffset);
+  return TableA.endTableA(builder);
+}
+
+serialize():Uint8Array {
+  return this.bb!.bytes();
+}
+
+static deserialize(buffer: Uint8Array):TableA {
+  return TableA.getRootAsTableA(new flatbuffers.ByteBuffer(buffer))
+}
+
+unpack(): TableAT {
+  return new TableAT(
+    (this.b() !== null ? this.b()!.unpack() : null)
+  );
+}
+
+
+unpackTo(_o: TableAT): void {
+  _o.b = (this.b() !== null ? this.b()!.unpack() : null);
+}
+}
+
+export class TableAT implements flatbuffers.IGeneratedObject {
+constructor(
+  public b: TableBT|null = null
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  const b = (this.b !== null ? this.b!.pack(builder) : 0);
+
+  return TableA.createTableA(builder,
+    b
+  );
+}
+}