More Disk I/O autoinstrumentation

[romtsn]

While implementing File I/O instrumentation, we realized that it will not cover most commons usecases like SharedPreferences or reading a file from assets, so we will need to plan for those separately. Potential list of things to instrument:

• Scanner API (technically is a part of File I/O but rarely used in production, because it's slow)
• assets (context.getAssets())
• res/raw folder with raw resources like audio files and videos
• SharedPreferences

[marandaneto]

we could maybe split it out into different issues and link them together since all of them can be done separately and it'd take some time.

[marandaneto]

SharedPreferences is heavily used in Android apps, worth investigating if we can get spans out of every operation.