[V3] Fix Retain Cycles

[richherrera]

Summary of changes

• Remove all script handlers in deinit to avoid retain cycles in WebAuthenticationSession.
• Instead of POPPopupBridge handling WKWebView messages directly, WebViewScriptHandler now acts as an intermediary.
• WebViewScriptHandler receives messages from WKWebView and forwards them to proxy.
• The proxy property in WebViewScriptHandler is weak, helping prevent potential retain cycles.
• Add Unit Test

🐛

bug.mov

🧼

retain-cycles.mov

Checklist

• [ ] Added a changelog entry

Authors

• @richherrera

[jaxdesmarais]

Are we able to add a unit test for this? Not sure if it's easily testable now that it's fixed but not a blocker.

[richherrera]

Are we able to add a unit test for this? Not sure if it's easily testable now that it's fixed but not a blocker.

Sure, I added a new method to check for memory leaks. What I did was add the test and the extension in v3, then did the same in this branch. It seems the tests were successful.