Refactor languages to use CodeGenerator interface. (#7797)

* Refactor to use CodeGenerator interface.

- Move code to its own header file to be included in flatc_main.cpp
- Refactor code to use CodeGenerator interface for all languages

* Format all files

* remove lua code generator since it doesn't support bfbs generator

* Update CMakeLists file with new idl_gen_*.cpp and idl_gen_*.h files

* Add idl_gen_swift header file

* Add idl_gen_swift header file and update bazel file

* Remove CodeGenerator interface for idl_gen_text.*. Remove comments and extern declaration

* Reorder header and implementation files in CMakeLists.txt

* Add idl_gen_* header files to implementation files

* Update CMakeLists and remove unused import

Co-authored-by: Derek Bailey <derekbailey@google.com>

src/idl_gen_python.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2023 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FLATBUFFERS_IDL_GEN_PYTHON_H_
+#define FLATBUFFERS_IDL_GEN_PYTHON_H_
+
+#include "flatbuffers/code_generator.h"
+
+namespace flatbuffers {
+
+// Constructs a new Python code generator.
+std::unique_ptr<CodeGenerator> NewPythonCodeGenerator();
+
+}  // namespace flatbuffers
+
+#endif  // FLATBUFFERS_IDL_GEN_PYTHON_H_