Fix notification shell commands

- Notification posting is done as calling app
- make some only callable by shell

Test: atest
Test: sample app; make sure posted notification is from app itself
Test: sample app; make sure some commands fail
Test: make sure all modified commands still work from shell
Fixes: 143339775
Change-Id: I50ee768e792266ad2091f1913168e89d5d1463ed