Add ESLint (#941)

* Add eslint, switch to lint-staged for precommit

* Fix all ESLint errors

* Update GH workflow to check prettier and eslint

.husky/pre-commit

@@ -1,4 +1,4 @@
 #!/usr/bin/env sh
 . "$(dirname -- "$0")/_/husky.sh"
 
-npx pretty-quick --staged
+npx -y lint-staged