[non-fatal-anr-support] Investigate other means of checking the main thread #6210

Have a look at:

• tracing the main thread (is it stalling, why is it stalling/what's happening) instead of polling: https://blog.p-y.wtf/tracing-main-thread-messages
• Utilizing Looper.getMainLooper().dump();instead of mainthread.getStackTrace()
• Using internal APIs to retrieve the topmost entry from Looper.getMainLooper()directly
• Have a look into competitors implementation logic
• Have a look if we can collect external signals (e.g. device gets hot, causing CPU throttling, etc…)
• etc..

and see if they would provide any detailed value.

Out of scope:

• Having a look Perfetto System Traces, as this could be a project of it's own.

Timebox to 4d.