Strip an Attributed Details or Summary Opener Through TAGS in pr_review.py #3208

The shape

scripts/pr_review.py strips presentation tags from a printed block through TAGS, </?(?:details|summary)>, which unwrap and entry_heading both use. It matches a bare tag only, so an attributed opener such as <details open> or <summary class="x">, or a self-closed <summary/>, survives unwrap and prints raw in the digest. entry_heading likewise reads such a heading with its tag still on it.

The opener readers moved onto one boundary, tag_opener, in #3206. TAGS is the one opener reader left on a rule of its own. It was left out there because it is a stripper rather than a recognizer, and building it as tag_opener(...) plus [^>]*> would let a tag left open at a line's end swallow the prose after it.

Expected

TAGS strips an attributed or self-closed <details> or <summary> opener as it strips a bare one, ending the tag name where tag_opener does, and bounded so an unclosed tag strips nothing past its own line. A test pins <details open>, <summary class="x">, and <summary/> as stripped by unwrap, and <summaryx> as kept.

Found by the local review of #3206.