Fix "Export SVG" feature in next 14

[cmdcolin]

Next.js version 14 currently throws an error when trying to export svg. The svg rendering uses a function renderToStaticMarkup from "react-dom/server" and next js decided it doesn't like seeing that in client code. Using a recommendation from the react docs goes some way towards fixing https://react.dev/reference/react-dom/server/renderToString#removing-rendertostring-from-the-client-code

xref vercel/next.js#58533 (comment)
fixes GMOD/jbrowse-react-app-nextjs-demo#1

Note: We still use renderToString in the web worker. We do not document web worker usage of our embedded components under nextjs though, but if this ever happened (#3730 ) then it may run into this, and the workaround in this PR would not work because it assumes existence of a document which does not exist in the web worker

[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (6e061fe) 63.12% compared to head (13f90b0) 63.12%.

Files	Patch %	Lines
packages/core/util/index.ts	81.81%	2 Missing ⚠️
products/jbrowse-react-app/src/createViewState.ts	0.00%	2 Missing ⚠️
...view/src/BreakpointSplitView/svgcomponents/util.ts	91.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4136   +/-   ##
=======================================
  Coverage   63.12%   63.12%           
=======================================
  Files        1062     1064    +2     
  Lines       31044    31059   +15     
  Branches     7397     7399    +2     
=======================================
+ Hits        19595    19605   +10     
- Misses      11279    11285    +6     
+ Partials      170      169    -1     

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[cmdcolin]

other notes:

• this further makes @jbrowse/img dependent on jsdom, but it already did use jsdom so not really a change there.
• reading from innerHTML changes some attributes such as > to > which we then flip back manually. this doesn't seem ideal, but it does match snapshot tests after doing so