Setup skeleton of userrecoveryManagerService

This commit is to create a skeleton of new UserRecoveryManagerService as a platform Service.
The skeleton includes:

*   Aconfig flag `enable_user_recovery_manager` to be able to disable this service.
*   A new service that has a stub for IPC `IUserRecoveryManager.aidl` and a client side `UserRecoveryManager.java`
*  register the `UserRecoveryManagerService` in the systemServer

Bug: 415960504
Flag: android.app.userrecovery.flags.enable_user_recovery_manager
Test: Build the code and see that `enable_user_recovery_manager` works as expected and the service is started.
Change-Id: Ieb8819806c80bb7b432d7a7d2c9e4549cdf8219b