Add SMS over IMS APIs

- Adds public APIs that IMS providers will implement/use
- Adds aidl APIs for internal communications to support SMS over IMS.
- First pass at documentation of APIs.

Moving over from  ag/3265442

Bug: 69846044

Test: None
Change-Id: Ic665a2a7d64a56417bcf2a159d6b88b05cdb832a