Add waitForService to AIDL.

Eye towards:
- avoiding while(true) getService loops
- need it to make AIDL dynamic HALs
- need it for feature parity w/ HIDL

Bug: 136027762
Test: use in AIDL unit test
Change-Id: I2981eb4ebecff8c4519e09b7dcca51892dfd528d
3 files changed