[Mono] Revisit the signedness of the index argument of metadata methods #70495

Metadata methods to consider:

• mono_metadata_table_bounds_check in src\mono\mono\metadata\metadata-internals.h
• Return of table_info_get_rows in src\mono\mono\metadata\metadata-internals.h
• Return of mono_metadata_table_num_rows in src\mono\mono\metadata\metadata-internals.h
• mono_metadata_decode_table_row in src\mono\mono\metadata\metadata.c
• mono_metadata_decode_row_col in src\mono\mono\metadata\metadata.c
• mono_metadata_decode_row in src\mono\mono\metadata\metadata.c
• mono_metadata_decode_row_slow in src\mono\mono\metadata\metadata.c
• The local var which stores the return of mono_metadata_token_index
• end_idx of mono_metadata_methods_from_event should be guint32 * in src\mono\mono\metadata\metadata.c

The above ones are the ones that I observed, which may not be complete.