chore: forbid importing src/common/Events.ts (#6183)

This file is now deprecated and only used by the coverage tool and
DocLint - these tools will be updated to not rely on it in the future.

We now have events defined per class - e.g. all the events that `Page`
can emit are defined in the `PageEmittedEvents` enum, and similar. We
have to keep `Events.ts` around for the aforementioned tools, but don't
want its usage creeping back into our source code.

.eslintrc.js

@@ -84,7 +84,11 @@ module.exports = {
         "mocha/no-exclusive-tests": "error",
 
         // enforce the variable in a catch block is named error
-        "unicorn/catch-error-name": "error"
+        "unicorn/catch-error-name": "error",
+
+        "no-restricted-imports": ["error", {
+            patterns: ["*Events"],
+        }]
     },
     "overrides": [
         {