Introduce preferred notes mode config.

This config is used by the NoteTaskController to determine how to create
the notes task. In the case of stylus mode, the NoteTaskController adds
EXTRA_USE_STYLUS_MODE to the intent.

The default config value corresponds to the stylus mode, as the primary
notes role application is for tablets, where handwritten model is
assumed.

The configuration is an integer, extendable to other modes.

Change-Id: Idebe027e1a7996c6969d24e079cc4b02de33a669
Test: Manually on a Pixel phone.
Flag: build.RELEASE_PACKAGE_PREFERRED_NOTES_UI_MODE_OVERLAY
Bug: 370926837