Implement stream pooling and more fine grained lock

[Soreepeong]

When using multiple threads to call GetFile<T>, the lock was being held per SqPack, which effectively is a .dat file. Changed that to lock per file inside a .dat file, and added SqPackStreamPool? GameData.StreamPool which will reuse already opened file handles to avoid performance hit from creating handle per every file accessed.

The attached test code iterates 800,054 paths from 040000. The test was done on 16 P-threads on 13900k.

• Before: 30s
• After: 7.9s
• After + StreamPool: 6.8s

SqPackStreamPool_TestCode.txt
SqPackStreamPool_TestResult.txt

Notes

• Microsoft.Extensions.ObjectPool has been added as a dependency.
• GameData is now implements IDisposable, so that it disposes InstanceOfGameData.StreamPool along with it.
• SqPack.FileCache and SqPack.CacheLock are now obsolete, and they do nothing.