Added --filename-suffix and --filename-ext to flatc (#5778)

* Fixed refractoring issue in reflection/generate_code.sh. Also, mv deletes the original file, so I don't need to clean it up manually in that case.

* Added --filename-suffix and --filename-ext to flatc

* Fixed typo and added example generation of suffix and extension for C++

* Removed extra ;

* Removed clang-format block from a region that didn't need it. Fixed an auto format of another clang-format block

* Added docs, fixed pointer alignment, removed suffix test file

src/idl_gen_java.cpp

@@ -42,7 +42,7 @@ class JavaGenerator : public BaseGenerator {
  public:
   JavaGenerator(const Parser &parser, const std::string &path,
                 const std::string &file_name)
-      : BaseGenerator(parser, path, file_name, "", "."),
+      : BaseGenerator(parser, path, file_name, "", ".", "java"),
         cur_name_space_(nullptr) {}
 
   JavaGenerator &operator=(const JavaGenerator &);