[Role Logic Move] Lift user from grantSingle

This change modifies the following methods:

- Permissions::grantPermissionAndAppOp[AsUser]
- Permissions::revokePermissionAndAppOp[AsUser]
- Permissions::grantSingle[AsUser]
- Permissions::revokeSingle[AsUser]

...by making them multi-user aware. I.e., lift any references to
Process.myUserHandle() out of them into method arguments. Also,
modify all callers to use a single "UserHandle user" variable.

Bug: 302563690
Test: atest CtsRoleTestCases
Change-Id: If2a6623c395ba1c5cd04f79c1aa7aa6c4cc0bd66