Add methods to send connected/disconnected state.

Also add methods to set the legacy subtype and the APN name.
These have to be added together because they have to be used
together.

Bug: 138306002
Bug: 139268426
Test: atest FrameworksNetTests FrameworksWifiTests FrameworksTelephonyTests
Change-Id: Ie90b8d290eab490061d5cb066744b67d597b9469
Merged-In: Ie90b8d290eab490061d5cb066744b67d597b9469
(clean cherry-pick from internal branch)