Base implementation of WFC disclaimer UI

Test: manual - Check that no error occurred when changing the wifi
calling settings to turn on.
Test: auto - Passed WifiCallingSettingsForSubTest,
WifiCallingDisclaimerFragmentTest and DisclaimerItemListAdapterTest.
Bug: 67872298

Change-Id: I789f530d3e16baa6e56feaa4269f6696976f747e
Merged-In: I789f530d3e16baa6e56feaa4269f6696976f747e