Add clippy and format Github Actions.

[andriyDev]

Now pull requests will automatically determine if they satisfy clippy and rustfmt! I also fixed up all the clippy warnings so we're all green.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 87.50000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 98.2%. Comparing base (c8201e8) to head (900b2e7).

Additional details and impacted files

Files	Coverage Δ
src/astar.rs	93.9% <100.0%> (ø)
src/avoidance.rs	95.7% <100.0%> (+<0.1%)	⬆️
src/nav_data.rs	99.3% <100.0%> (-0.1%)	⬇️
src/path.rs	91.6% <100.0%> (-0.1%)	⬇️
src/pathfinding.rs	100.0% <100.0%> (ø)
src/lib.rs	91.3% <57.1%> (-1.1%)	⬇️