stringprep and IDNA 2003 incorrectly handles some characters

[sethmlarson]

Linked PRs

• gh-155292: Don't consider Unicode codepoint attributes outside RFC 3454 #155293
• [3.15] gh-155292: Don't consider Unicode codepoint attributes outside RFC 3454 (GH-155293) #156017
• [3.14] gh-155292: Don't consider Unicode codepoint attributes outside RFC 3454 (GH-155293) #156020