Handle 5G meteredness in telephony framework

Carriers can set override values via SubscriptionManager.
Added constants and configs for 5G meteredness updates.

Bug: 139070884
Bug: 139218397
Test: atest FrameworksTelephonyTests
Test: atest
cts/tests/tests/telephony/current/src/android/telephony/cts/SubscriptionManagerTest.java

Change-Id: Ic8c5938c4a414ce63303a1fa25af60a0082b1ba9