feat(ConflictPicker): move conflict picker dialog from @nextcloud/upload

[susnux]

• part of [RFC] export of vue components nextcloud-upload#1809

[codecov]

Codecov Report

❌ Patch coverage is 0% with 40 lines in your changes missing coverage. Please review.
✅ Project coverage is 42.94%. Comparing base (95c159f) to head (c06629b).
⚠️ Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/conflict-picker.ts	0.00%	38 Missing and 1 partial ⚠️
lib/index.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1971      +/-   ##
==========================================
- Coverage   45.27%   42.94%   -2.33%     
==========================================
  Files          21       22       +1     
  Lines         740      780      +40     
  Branches       92       93       +1     
==========================================
  Hits          335      335              
- Misses        405      444      +39     
- Partials        0        1       +1     

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