Add AppFuseMountException

StorageManagerService and AppFuseBridge are used
NativeDaemonConnectorException to represent app fuse mount
failure. But NativeDaemonConnectorException is part of NSD
module files and it will be moved to the Connectivity module.
Thus, create AppFuseMountException to separate the usage and
make the exception more precisely.

Bug: 206702844
Test: m
Change-Id: I8b0224ce8894bc68b082dcdba054e2ccc22869ef