Vote for userPreferredMode

Previously userPreferredMode was sent via defaultMode
to DisplayModeDirector. Now DisplayModeDirector needs
a way to understand whether the mode is the default
or userPreferredMode. This is important for creating
the userPreferredMode vote only for user preferred and
not the default mode.

With this CL, DisplayModeDirector creates the
user preferred mode vote with a predefined priority.

Change-Id: I0d24391f1c9938e3e49ee219bb040e4ade7794e0
Test: atest com.android.server.display.mode
Bug: 242093547