Backport "Support src filter in -WConf (Closes #17635) (#18783)"#20282

mkurz wants to merge 3 commits intoscala:lts-3.3scala/scala3:lts-3.3from

mkurz:wconf-src_3.3.xmkurz/dotty:wconf-src_3.3.xCopy head branch name to clipboard