Enable StrictMode security tool

[irfano]

StrictMode is a developer tool which detects things you might be doing by accident and brings them to your attention so you can fix them. Currently, it's commented in WordPressDebug.
We had a security vulnerability (Slack ref: p1656678398776749-slack-CRA4UEQQ3) caused by unsafe intent launch which could be detected by StrictMode's detectUnsafeIntentLaunch().
In this issue, we need to

• add detectUnsafeIntentLaunch() in StrictMode detections,
• investigate other detections that might be beneficial,
• check if enabling StrictMode have any significant drawback, if not, enable it for all debug builds,
• enable StrictMode detections in automated tests of CI,
• investigate other security tools. (If we can find good tools, we can use them in place of StrictMode or addition to StrictMode)

If these are a lot for a PR, multiple PRs can fix this issue.