mrc-6180 Add vite and other updates

[EmmaLRussell]

Very similar to the random-js updates PR:

• vitest rather than jest
• use vite build
• update gha versions
• update node version
• coverage update
• eslint rather than tslint
• format with prettier
• update all packages

A couple of variables/consts were removed as the linter showed up that they weren't ever used.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (e0c4790) to head (d61f70d).
Report is 11 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master       #23   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           11        10    -1     
  Lines          491       453   -38     
  Branches        66        60    -6     
=========================================
- Hits           491       453   -38     

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