Use Jupyter Packaging

[jtpio]

• Use the build backend and functions from jupyter_packaging and remove setupbase.py
• Move static config to setup.cfg
• Switch to tbump for version bumping
• Add check-manifest support

[codecov-io]

Codecov Report

Merging #477 (43384a3) into master (940bd2e) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #477      +/-   ##
==========================================
+ Coverage   77.77%   77.81%   +0.04%     
==========================================
  Files         106      106              
  Lines        9137     9138       +1     
  Branches      979      979              
==========================================
+ Hits         7106     7111       +5     
+ Misses       1681     1678       -3     
+ Partials      350      349       -1     

Impacted Files	Coverage Δ
jupyter_server/_version.py	100.00% <100.00%> (ø)
jupyter_server/tests/services/kernels/test_api.py	97.05% <0.00%> (-1.97%)	⬇️
jupyter_server/services/kernels/handlers.py	58.51% <0.00%> (+1.59%)	⬆️

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[blink1073]

Thanks! 🚀