feat: allow multiline matching and double quotes in regexp expression

[Rational-Curiosity]

Example of tmux regexp capturing quotes:

set-option -g @thumbs-regexp-1 "(?:^|[^\\\\])(\"(?:\\\\\"|[^\"\n])*[^\\\\\n]\"|'(?:\\\\'|[^'\n])*[^\\\\\n]'|`(?:\\\\`|[^`\n])*[^\\\\\n]`)"