[Starfish] Add more app-start related spans

[markushi]

Description

There are a few more relevant app-launch related metrics which we could include for measuring cold start app times. Papa showcases some good examples.

[markushi]

Quoting @romtsn

these would make a perfect hierarchy :smile: -- process fork/start span -- bindApplication span -- first class load span -- class loader created span -- ContentProviders -- Application.onCreate -- Activities