Add Code Generator for idl_gen_fbs to parse .proto files (#7832)

* Add code generator for proto files

* Update

* Add --proto to script

* Remove cmt

* Move proto parsing logic into else block to share same set up logic for code_generator

* Remove IsValidCodeGenerator

scripts/generate_code.py

@@ -105,6 +105,7 @@ PHP_OPTS = ["--php"]
 DART_OPTS = ["--dart"]
 PYTHON_OPTS = ["--python"]
 BINARY_OPTS = ["-b", "--schema", "--bfbs-comments", "--bfbs-builtins"]
+PROTO_OPTS = ["--proto"]
 
 # Basic Usage
 
@@ -192,6 +193,11 @@ flatc(
     data="monsterdata_test.json",
 )
 
+flatc(
+    PROTO_OPTS,
+    schema="prototest/test.proto",
+)
+
 # For Rust we currently generate two independent schemas, with namespace_test2
 # duplicating the types in namespace_test1
 flatc(