Make a customized context when matching a record in MccMncOverrideInfo

MccMncOverrideInfo records the customized carrier id, visited
mccmnc, home mccmnc. Once the carrier id and sim's mccmnc are
matching a record in MccMncOverrideInfo, make a customized
context by changing the mcc/mnc of configuration.

Bug: 147075795
Test: atest NetworkStackTests:NetworkMonitorTest
Change-Id: I75924f60c637eb93ac99b14b333608b6faeaa24a
Merged-In: I20f3c291015a0a79d88e923438d39ff90e1f0752
(cherry picked from commit 6d0b27f8)