Provide RRO configuration to send DHCP client hostname option.

Add a configurable option in the RRO which controls whether or not to
send the hostname set in the Settings->About phone->Device name. The
option in RRO is false by default, that means DHCP Request still not
include any hostname by default. Once the option is overlaid and enabled,
the device name after transliteration will be wrote into hostname option.

Bug: 131783527
Test: atest NetworkStackTests NetworkStackIntegrationTests
Test: manual test, create empty APK to overlay the RRO configuration.

Change-Id: I9af0b0d9e7bb526d3a3c1003bb99d0a3d69b1e9e