deps: Update to React Router v6 and React 18

[nellh]

All the required updates to move to the latest release of React Router, unlocking some blocked upgrades for other dependencies (including React 18).

Fixes #2657 and #2656

[nellh]

Looks like tests hang in CI, working on it.

[nellh]

Looks like tests hang in CI, working on it.

Fixed these now.

[codecov]

Codecov Report

Merging #2661 (d1bbcfc) into master (bb9e722) will increase coverage by 0.29%.
The diff coverage is 11.11%.

@@            Coverage Diff             @@
##           master    #2661      +/-   ##
==========================================
+ Coverage   39.37%   39.67%   +0.29%     
==========================================
  Files         562      562              
  Lines       34408    34268     -140     
  Branches      903      910       +7     
==========================================
+ Hits        13549    13595      +46     
+ Misses      20734    20548     -186     
  Partials      125      125              

Impacted Files	Coverage Δ
packages/openneuro-app/src/client.jsx	0.00% <0.00%> (ø)
...neuro-app/src/scripts/common/containers/header.tsx	0.00% <0.00%> (ø)
...euro-app/src/scripts/datalad/mutations/publish.jsx	0.00% <0.00%> (ø)
...uro-app/src/scripts/datalad/mutations/snapshot.tsx	0.00% <0.00%> (ø)
...pp/src/scripts/datalad/routes/dataset-redirect.tsx	0.00% <0.00%> (ø)
...penneuro-app/src/scripts/dataset/dataset-query.jsx	0.00% <0.00%> (ø)
...enneuro-app/src/scripts/dataset/dataset-routes.jsx	0.00% <0.00%> (ø)
...nneuro-app/src/scripts/dataset/draft-container.tsx	0.00% <0.00%> (ø)
...-app/src/scripts/dataset/draft-snapshot-routes.tsx	0.00% <0.00%> (ø)
...euro-app/src/scripts/dataset/mutations/publish.jsx	0.00% <0.00%> (-49.16%)	⬇️
... and 32 more

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[effigies]

LGTM