Use pre-commit to run code checks (also in CI)

[erlendvollset]

This PR enables running code checks as pre-commit hooks for a shorter feedback loop. Install the hooks by running:

pre-commit install

We also now run all the code checks as part of the CI pipeline.

I took the liberty of adding isort and autoflake aswell - these will sort and remove unused imports.

[codecov[bot]]

Codecov Report

Merging #8 (1705182) into main (786df45) will increase coverage by 0.03%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
+ Coverage   80.16%   80.19%   +0.03%     
==========================================
  Files          37       37              
  Lines        2112     2111       -1     
==========================================
  Hits         1693     1693              
+ Misses        419      418       -1     

Impacted Files	Coverage Δ
expression/collections/map.py	60.27% <ø> (ø)
expression/core/aiotools.py	62.79% <ø> (+1.42%)	:arrow_up:
expression/__init__.py	100.00% <100.00%> (ø)
expression/collections/maptree.py	58.64% <100.00%> (ø)