Add pixel_pitch parameter that must be updated per device

Pixel pitch is the number of microns per pixel on device.
This is used to size the UDFPS icon.

Bug: 319894241
Flag: ACONFIG com.android.systemui.device_entry_udfps_refactor DEVELOPMENT
Test: manual
Change-Id: Idb2b01ae7115117b20651bdd4959b67c0b92b166