Add xDpi and yDpi to DisplayViewport

This change adds and populates xDpi and yDpi fields to the
DisplayViewport from DisplayDeviceInfo.

Corresponding JNI layer is updated to read these new values and
propogate to the native input code.

Test: check dumpsys input
Bug: 432649760
Flag: com.android.input.flags.use_separate_xy_dpi_scaling_for_mice
Change-Id: I0f5104e6a80c894907c294ebdef96c8d025aa09e