Editor: Merge Editor bug fixes ahead of 6.5 RC4.
This merges several high priority bug fixes for the editor ahead of WordPress 6.5:
Props youknowriad, annezazu, mcsf, jsnajdr, mmaattiiaass, get_dave, scruffian, mikachan, grantmkin, andraganescu, scruffian, antosguillamot, fabiankaegy, huzaifaalmesbah, krupajnanda, colorful-tones, liviopv, mamaduka, kim88, poena, peterwilsoncc, wildworks, swissspidy, desrosj, jorbin.
Fixes #60315.