[Task] Use uncompressed file buffer for SaveState reload when RAM suffice

[elad335]

SaveState creation uses multiple threads for at saving, but only one for reloading. ZSTD is less suitable for multi threaded loading, although it is possible. A short-term goal for optimizing savestate reload would be to use an unvompressed file buffer in RAM when saving and reusing it for the reload process. Because decompression is slow. The requirement would be that there is at least 2GB of RAM currently available and +16GB in total.

[kd-11]

Maybe 7z makes more sense?