forked from minhngoc25a/yt-dlc

- Introduce _BASE_URL in RaiBaseIE class so it could be reused as base for the several subextractors. - Remove first test of RaiPlayIE, it is no longer available - Adjust RaiPlayIE to recent raiplay.it updates, make it extension agnostic (passing possible `.json' URLs is now supported too) and update test info_dict. - Adjust RaiPlayLiveIE to recent raiplay.it updates. Passing it as `url_transparent' is no longer supported (there is no longer an accessible ContentItem) - Adjust RaiPlayPlaylistIE to recent raiplay.it updates and instruct it about ContentSet-s. - Update a RaiIE test and remove two tests that are no longer availables This fix issue #22923, #22906 and supersedes #23006.