Move font size related resources to SettingsLib (1/2)

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 resource 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: Ia2621e3b4c71f900e6591644d0e3f93bedbe4ee8
Merged-In: If630bd9c9c27823c210410b53342b921a11bbfb9