Create v1.2.0.md, draft of release announcements

[elliothershberg]

We are planning on releasing in ~30 minutes, check it out and let us know any feedback or additional features worth highlighting 👍

[codecov]

Codecov Report

Merging #1935 (898e578) into main (4d42689) will decrease coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1935      +/-   ##
==========================================
- Coverage   58.80%   58.70%   -0.10%     
==========================================
  Files         460      460              
  Lines       21735    21735              
  Branches     5198     5198              
==========================================
- Hits        12781    12760      -21     
- Misses       8653     8674      +21     
  Partials      301      301              

Impacted Files	Coverage Δ
...-view/src/SpreadsheetView/models/FilterControls.ts	20.00% <0.00%> (-15.56%)	⬇️
...et-view/src/SpreadsheetView/models/ImportWizard.ts	59.79% <0.00%> (-11.35%)	⬇️
...view/src/SpreadsheetView/models/SpreadsheetView.ts	31.88% <0.00%> (-5.80%)	⬇️
packages/core/util/index.ts	79.17% <0.00%> (+0.27%)	⬆️

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