ApnEditor: Consider subId when reading carrier config

Considers subId when reading carrier config values
KEY_READ_ONLY_APN_TYPES_STRING_ARRAY and
KEY_READ_ONLY_APN_FIELDS_STRING_ARRAY.

This ensures that the APN will be editable or non-editable correctly
when using dual sim.

Bug: 112929355
Test: Manual
Change-Id: I2186dd5e1f71ca5361309a7314f84cf4fa2d3937
1 file changed