Fix race condition with async API operations

[neolynx]

Fixes #1376

Description of the Change

• fix race condition with rasync background operations
• Do all relevant database reading inside maybeRunTaskInBackground.
• Notably, LoadComplete will load the reflist of a repo. if this is done outside of a background operation, the data might be outdated when the background tasks runs.

[codecov]

Codecov Report

Attention: Patch coverage is 47.05882% with 45 lines in your changes missing coverage. Please review.

Project coverage is 74.89%. Comparing base (0e6f9c3) to head (f16a68f).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
api/publish.go	59.09%	13 Missing and 5 partials ⚠️
api/snapshot.go	28.57%	10 Missing and 5 partials ⚠️
api/repos.go	40.00%	8 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1380      +/-   ##
==========================================
+ Coverage   74.84%   74.89%   +0.04%     
==========================================
  Files         151      151              
  Lines       17161    17161              
==========================================
+ Hits        12845    12852       +7     
+ Misses       3292     3284       -8     
- Partials     1024     1025       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.