Dialog: Simulate volatile memory lock behavior

[unknownbrackets]

See notes in #13765. While not using a thread (which is likely more correct), this largely simulates the observable behavior for most dialogs. It also prevents state changes until the lock is acquired, which might be important for timing things in some games.

Should help #8288.

-[Unknown]

[Panderner]

Crisis Core and Wall-E broke this PR unfortunately

[Nanoposan69]

GTA LCS and VCS is now broken too.

[unknownbrackets]

Hm, it seems like that might require respecting thread priority. What it seems to do:

1. Run savedata calls on a better priority thread.
2. Sleep the savedata calls thread after calling shutdown.
3. On a worse priority thread, wakeup the savedata thread.
4. Close things down and try to lock volatile.

It does a "try" which fails, instead of blocking. If it had used sceKernelVolatileMemLock, everything would've been fine, but it just assumes the try succeeds.

-[Unknown]