Add API for batch fetching game title information

[mariobob]

Added a new rc_client API for fetching game titles and badge names.

New API

rc_client_async_handle_t* rc_client_begin_fetch_game_titles(
  rc_client_t* client, const uint32_t* game_ids, uint32_t num_game_ids,
  rc_client_fetch_game_titles_callback_t callback, void* callback_userdata);

void rc_client_destroy_game_title_list(rc_client_game_title_list_t* list);

This allows consumers to fetch game title information (including badge names for game icons) through the rc_client interface rather than using rc_api directly, consistent with other fetch operations like rc_client_begin_fetch_hash_library and rc_client_begin_fetch_all_user_progress.

Testing

Tested in Duckstation in stenzek/duckstation#3658