Move font size related resources to SettingsLib (2/2)

Since creating the seekbar for changing font size in SystemUI requires
the size of the value entry array and the values in the array.
Therefore, we move the related resources to SettingsLib to share the usage.

Bug: 242326166
Test: make RunSettingsRoboTests ROBOTEST_FILTER=FontSizeDataTest
Test: Maually test the availability of changing font size through
Settings page

Change-Id: I41587c74844e45919775753326dd329779d6b6e8
Merged-In: Ic0ca23142e2c710400a936d4f1030ec30f736a35