Tools: Add complexity rule

.eslintrc.js

@@ -63,6 +63,10 @@ module.exports = {
 		'no-array-constructor': ['error'],
 		'radix': ['error'],
 
+		// Warn only for now because fixing everything would take too much
+		// refactoring, but new code should try to stick to it.
+		'complexity': ['warn', { max: 10 }],
+
 		// Checks rules of Hooks
 		'react-hooks/rules-of-hooks': 'error',
 		// Checks effect dependencies