Allow AMS fgs notification rate limit with ALLOWLIST permission

Android 16 limits the shell user to only modify the DeviceConfig
flags that have been allowlisted; to support this, the
WRITE_DEVICE_CONFIG permission will be removed from the shell user.
Some CTS tests adopt the shell permission identity to invoke the AMS
service method enableFgsNotificationRateLimit which is currently
guarded with the WRITE_DEVICE_CONFIG permission. To support these
tests, this commit updates this method to also allow the action if
the caller has the WRITE_ALLOWLISTED_DEVICE_CONFIG permission.

Bug: 364083026
Flag: android.security.protect_device_config_flags
Test: atest ServiceTest
Change-Id: I7ac4d3d92a73bc60546bbfcb9c9d5469004f76ce