Fixes issues and tests on indexes

[brichet]

This PR :

• updates indexes after each way to upload or delete a package
• adds some tests on update indexes function
• adds tests on duplicate upload, with and without force flag
• adds some tests on repodata.json file after deleting a package

[codecov-commenter]

Codecov Report

Merging #555 (6a41176) into main (bee4a48) will decrease coverage by 0.82%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #555      +/-   ##
==========================================
- Coverage   82.87%   82.04%   -0.83%     
==========================================
  Files          78       78              
  Lines        5973     5977       +4     
==========================================
- Hits         4950     4904      -46     
- Misses       1023     1073      +50     

Impacted Files	Coverage Δ
quetz/main.py	86.70% <100.00%> (+0.50%)	⬆️
quetz/pkgstores.py	42.45% <0.00%> (-11.60%)	⬇️

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[wolfv]

Thank you @brichet this looks great!