fix: add configFile option

[diefans]

This fixes #345, by adding a configFile option to change the default (.pre-commit-config.yaml) and so enables the parallel usage of devenv and non-devenv maintained pre-commit hooks.

[sandydoo]

1. There are a few more pre-commit calls in run that would need to be adjusted.

   git-hooks.nix/modules/pre-commit.nix

   Lines 55 to 83 in 6d7586d

   	run =
   	runCommand "pre-commit-run" { buildInputs = [ git ]; } ''
   	set +e
   	HOME=$PWD
   	# Use `chmod +w` instead of `cp --no-preserve=mode` to be able to write and to
   	# preserve the executable bit at the same time
   	cp -R ${cfg.rootSrc} src
   	chmod -R +w src
   	ln -fs ${configFile} src/.pre-commit-config.yaml
   	cd src
   	rm -rf .git
   	git init -q
   	git add .
   	git config --global user.email "[email protected]"
   	git config --global user.name "Your Name"
   	git commit -m "init" -q
   	if [[ ${toString (compare install_stages [ "manual" ])} -eq 0 ]]
   	then
   	echo "Running: $ pre-commit run --hook-stage manual --all-files"
   	${cfg.package}/bin/pre-commit run --hook-stage manual --all-files
   	else
   	echo "Running: $ pre-commit run --all-files"
   	${cfg.package}/bin/pre-commit run --all-files
   	fi
   	exitcode=$?
   	git --no-pager diff --color
   	mkdir $out
   	[ $? -eq 0 ] && exit $exitcode
   	'';

2. I'm not sure about the name of the option. We may also need to expose configFile itself in the future, e.g. feat: update pre-commit.nix to be "run" customizable #494. Maybe configPath would be better?