Migrate File to statslib
Updates:
- media.thumbnail.generate.bucket
- media.thumbnail.generate.fetchoriginal
- media.thumbnail.generate.store
- media.thumbnail.generate.transform
This doesn't attempt to label the multiple generate methods
becuase they appear to me to have very heterogeneous
functionality
Patches squashed into this commit:
- I652f31fd8a553b8f197fb51ffd2cca34199c7394
- I8edc96668b4e5968b8b44dc92fe4fdc3f29fcbab
- I8edc96668b4e5968b8b44dc92fe4fdc3f29fcbab
Bug: T359344
Change-Id: Icec6600b4751568ef93f9fbe9e2063770d405bcb