chore: replace standard with eslint-config-standard and add custom rules (#14636)

* chore: replace standard with eslint-config-standard

This adds support for --cache so linting JS only takes ~1 second and only lints things that changed

It also allows us to add custom linting rules

* chore: add eslint-plugin-mocha and enable the no-exclusive-tests rule

This will block anyone from pushing / merging a `.only` test or describe

.gitignore

@@ -60,3 +60,6 @@ electron.d.ts
 
 # Spec hash calculation
 spec/.hash
+
+# Eslint Cache
+.eslintcache