Fix 'backend' usage in DPLR kernel

Fix bug in S4Block stepping

Merge pull request #111 from HazyResearch/autoformat

remove requirements.txt from Linting CI - it is not required to run the lint check

delete coverage file

increase line length to 100

add ci

add docformatter for dev requirements

add Makefile

add flake8, black, isort and precommit for autoformatting

[Infra] Update to pytorch-lightning 2.0

[Infra] Disable bias weight decay and log params per optimizer group

Update logic for real-valued SSM (S4D-Real)

[S4] Update S4D 'kernel' to 'backend' parameter rename in standalone

[S4] Let S4Block use a generic layer instantiated from registry