feat: add Array.prototype.groupBy/groupByToMap

[dnalborczyk]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:

Description

stage 3: https://github.com/tc39/proposal-array-grouping

[codecov]

Codecov Report

Merging #4360 (c9f5dfb) into master (042933a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4360   +/-   ##
=======================================
  Coverage   98.70%   98.70%           
=======================================
  Files         205      205           
  Lines        7320     7320           
  Branches     2083     2083           
=======================================
  Hits         7225     7225           
  Misses         35       35           
  Partials       60       60           

Impacted Files	Coverage Δ
src/ast/nodes/shared/ArrayPrototype.ts	100.00% <ø> (ø)

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[lukastaegert]

👍