Add brandOverride back to IccRecord

During the spn refactor ag/7013869, we remove the brand override from
IccRecord. This will cause a problem when the ApnSettingUtils use spn to
match mvno.

We add the brandOverride back to the IccRecord and create a method to
get the service provider with brandOverride.

Bug: 139056894
Test: build
Change-Id: I041dce4d55c79442d81053ff9410de81803e9b08