WIP: enh: use @nextcloud/y-http provider

[max-nextcloud]

This is still work in progress. Just created the PR to track TODOs and so on.

Fixes#7283.

[codecov]

Codecov Report

Attention: Patch coverage is 99.48187% with 1 line in your changes missing coverage. Please review.

Project coverage is 59.05%. Comparing base (72e3453) to head (97d23a2).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/components/Editor/GuestNameDialog.vue	0.00%	1 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #7311 +/- ##
==========================================
+ Coverage 52.18% 59.05% +6.86% 
==========================================
Files 483 484 +1 Lines 41918 37095 -4823 Branches 1047 1047 ==========================================
+ Hits 21875 21905 +30 + Misses 19940 15087 -4853 
Partials 103 103 

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[max-nextcloud]

A lot of prep work landed in main since and there's no point in rebasing this PR. Better rebuild the commits on top of what we have now.