Add APIs for available memory on eUICC.

Add an API that allows other apps to know about the available
non-volatile memory on the eUICC. When querying the api, the
app needs to have: READ_PHONE_STATE permission or
READ_PHONE_STATE_PRIVILEGED or carrier privilege.

Bug: 312793756
Test: m, atest EuiccServiceTest EuiccConnectorTest EuiccControllerTest EuiccManagerTest CtsTelephony2TestCases
Change-Id: Ibbb2cdd9edee188e328c6e0eebe8e436ec355d1e