Add slot based ICC channel APIs

These are SystemApis which require MODIFY_PHONE_STATE, and can be used
to open ICC channels when there is no available subscription, using the
slot index instead of subId.

Bug: 126578014
Test: builds
Change-Id: I3f47a8ac07813ea9e326c7d76123352708bfeea2
Merged-In: I3f47a8ac07813ea9e326c7d76123352708bfeea2