Move entryvalues_font_size 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 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: If630bd9c9c27823c210410b53342b921a11bbfb9