User: Invalidate `user_activation_key` on password update.
Query: Ensure that only a single post can be returned on date/time based queries.
Block Editor: Coding standards, properly escape class names.
Cache API: Ensure proper escaping around the stats method in the cache API.
Formatting: Expand `sanitize_file_name` to have better support for utf8 characters.
Brings the changes in [47633], [47634], [47635], [47636], [47637], and [47638] to the 5.4 branch.
Props: aduth, batmoo, ehti, ellatrix, jorgefilipecosta, nickdaugherty, noisysocks, pento, peterwilsoncc, sergeybiryukov, sstoqnov, talldanwp, westi, westonruter, whyisjake, whyisjake, xknown.
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