Backport "Fix pkg obj prefix of opaque tp ext meth" to 3.3 LTS#584

tgodzik wants to merge 3 commits intolts-3.3scala/scala3-lts:lts-3.3from

backport-lts-3.3-21527scala/scala3-lts:backport-lts-3.3-21527Copy head branch name to clipboard