rc perl: Don't highlight regex, fix string escapes
rc perl: Don't highlight regex, fix string escapes

Highlighting perl regex patterns with regular expressions (with
highlighters) caused several misses that made most of the file
unreadable. This commit makes `perl.kak` not try to highlight
those patterns in the code, and also addresses issues with string
highlighting.

Somasis/kakoune,danr/kakoune,alexherbo2/kakoune,jkonecny12/kakoune,lenormf/kakoune,casimir/kakoune,jjthrash/kakoune,danr/kakoune,occivink/kakoune,alexherbo2/kakoune,mawww/kakoune,mawww/kakoune,casimir/kakoune,jjthrash/kakoune,lenormf/kakoune,lenormf/kakoune,alexherbo2/kakoune,jjthrash/kakoune,mawww/kakoune,Somasis/kakoune,alexherbo2/kakoune,jkonecny12/kakoune,casimir/kakoune,occivink/kakoune,danr/kakoune,casimir/kakoune,danr/kakoune,occivink/kakoune,occivink/kakoune,jjthrash/kakoune,jkonecny12/kakoune,Somasis/kakoune,Somasis/kakoune,jkonecny12/kakoune,lenormf/kakoune,mawww/kakoune