Make MUI + react-i18next peer dependencies

[cbeer]

React isn't sharing contexts across plugins + apps the way it used to (because webpack did something special? React 18 changed something?). In order to get shared contexts, Mirador (we believe) has to treat those as peer dependencies and require the installing app to provide them (like we're already doing for React etc).

... but that's slightly annoying for people who use the UMD build ("just render me a mirador"), so this PR also adds a separate Vite configuration that (should?) include all the peer dependencies so it can be used directly 🤷‍♂️ .

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 55 lines in your changes missing coverage. Please review.

Project coverage is 94.76%. Comparing base (20f12e1) to head (17439b0).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
vite-umd.config.js	0.00%	54 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4113      +/-   ##
==========================================
- Coverage   94.94%   94.76%   -0.19%     
==========================================
  Files         317      318       +1     
  Lines       16006    16061      +55     
  Branches     2501     2510       +9     
==========================================
+ Hits        15197    15220      +23     
- Misses        805      836      +31     
- Partials        4        5       +1     

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[cbeer]

Merging this per today's committers meeting