Build ethernet framework source into framework-connectivity-tiramisu

- move ethernet APIs, build it into framework-connectivity-tiramisu
- start ethernet service from ConnectivityServiceInitializer
- fix EthernetManager dependnecy in Tethering module
- fix EthernetNetworkSpecifier dependency in framework-connectivity
- fix the ethernet related config resource

Bug: 210586283
Test: m
Test: atest FrameworksNetTests EthernetServiceTests
Ignore-AOSP-First: Topic of Ethernet Mainline has merge conflict with
                   master, merge this CL first and cherry-pick it back.
Change-Id: I54857b8517649048a343c72797668394d5225766