[RUMF-1356] selectors using stable attributes and no class names

[BenoitZugmeyer]

Motivation

Explore various selector strategies for heatmaps. Don't use class names in CSS selector, as they might be unreliable in some cases.

Changes

Implement a new selector without class names.

Testing

• Local
• Staging
• Unit
• End to end

---

I have gone over the contributing documentation.

[codecov-commenter]

Codecov Report

Merging #1689 (99b4697) into main (ec6b18e) will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1689      +/-   ##
==========================================
+ Coverage   90.47%   90.50%   +0.02%     
==========================================
  Files         128      128              
  Lines        4779     4779              
  Branches     1067     1067              
==========================================
+ Hits         4324     4325       +1     
+ Misses        455      454       -1     

Impacted Files	Coverage Δ
...EventsCollection/action/getSelectorsFromElement.ts	100.00% <ø> (ø)
packages/core/src/tools/timeUtils.ts	100.00% <0.00%> (+2.70%)	⬆️

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