[Swift] Adds GRPC to Swift (#5758)

* Adds the basic structure for required to add grpc support

Added the message implementation

Updated the code to confirm to the protocol flatbuffersobject

Adds an example for Swift flatbuffers GRPC

Started implementing the swift GRPC code Gen

Generator generates protocols now

Fixing ci issues

Migrated the logic to use grpc_generator::File instead of string

Refactored swift project

Implemented GRPC in swift

Finished implementing GRPC in swift

Fixes issues

Adds contiguousBytes initializer to swift

Adds documentation + fixes buffer nameing in tables + structs

Adds documentation + fixes buffer nameing in tables + structs

Updated tests

* Updated version

include/flatbuffers/idl.h

@@ -1124,6 +1124,12 @@ bool GenerateJavaGRPC(const Parser &parser, const std::string &path,
 bool GeneratePythonGRPC(const Parser &parser, const std::string &path,
                         const std::string &file_name);
 
+// Generate GRPC Swift interfaces.
+// See idl_gen_grpc.cpp.
+extern bool GenerateSwiftGRPC(const Parser &parser,
+                    const std::string &path,
+                    const std::string &file_name);
+
 }  // namespace flatbuffers
 
 #endif  // FLATBUFFERS_IDL_H_