search: interpret escaped parentheses in heuristic

Created by: rvantonder

DO NOT REVIEW, WIP. Description is for myself.

Stacked on #11128.

This PR changes a function that controls a heuristic when interpreting syntax like () as patterns versus expression groups. When this heuristic encounters escaped parentheses, like \(\), it will interpret these (including slashes). We want to actually interpret this escape sequence here, since if this heuristic fires, it implies that the string is literal.

Created by: codecov[bot]

Codecov Report

Merging #11129 into master will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master   #11129   +/-   ##
=======================================
  Coverage   46.39%   46.39%           
=======================================
  Files        1367     1367           
  Lines       77136    77136           
  Branches     6553     6606   +53     
=======================================
  Hits        35786    35786           
  Misses      37951    37951           
  Partials     3399     3399           

Flag	Coverage Δ
#go	50.47% <100.00%> (ø)
#storybook	6.88% <ø> (ø)
#typescript	35.84% <ø> (ø)
#unit	46.18% <100.00%> (ø)

Impacted Files	Coverage Δ
internal/search/query/parser.go	91.94% <100.00%> (ø)