ISOFileSystem support for umd0:umd0

Allows Bleach: Soul Carnival 2 to find what it's looking for in its boot process (umd0:umd0). The game is still stuck in a blackscreen, but the boot process seems better than before (judging from the logs).

Prior to requesting umd0:umd0 the log is interesting. This is the second game I've seen waiting within a callback, and having something other than hleDelayResultFinish waking up an HLE-blocked thread.