fix: add support for equals on locale proxies

[ST-DDT]

For some strange reason, both toEqual() and not.toEqual() don't work on locale proxies.
This PR fixes that. There might be some internal magic at play.
See the commit with the test for more details about the error.

[codecov]

Codecov Report

Merging #2092 (0c69cd0) into next (76c3080) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 0c69cd0 differs from pull request most recent head 1985111. Consider uploading reports for the commit 1985111 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             next    #2092   +/-   ##
=======================================
  Coverage   99.59%   99.60%           
=======================================
  Files        2541     2541           
  Lines      242800   242806    +6     
  Branches     1249     1254    +5     
=======================================
+ Hits       241827   241836    +9     
+ Misses        946      943    -3     
  Partials       27       27           

Impacted Files	Coverage Δ
src/locale-proxy.ts	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes