attempt to fix some memory leaks

[otavepto]

this introduces a simple/cheap managed memory allocator, each allocated object is given a due/deadline time, after which the object is deallocated.
this memory manager relies on constant polling, just like the rest of the steam ecosystem, meaning that it doesn't spawn any threads and so it becomes the responsibility of the containing class.

if the containing class failed to perform this polling operation, the behavior becomes similar to simply using the new operator and storing the addresses (as if we were using std::vector<void *>), and since the allocator stores a reference to all allocated objects at least they will be deallocated once the containing class itself is destroyed.

I don't know for how long should these objects stay alive though, so I set each one to a comically large number.

used in:

• Steam_Remote_Storage::GetFileNameAndSize() (also removes the 300 chars filename limit)
• Steam_Matchmaking_Servers::GetServerDetails()
• Steam_Remote_Storage::GetUGCDetails()

feel free to reject this PR if it seems unsafe, it's understandable that this might be problematic.

[Detanup01]

Need to test the stuff if good or not. (So games doesn't break with it, etc)
Desposing after class disposed is good.

[Detanup01]

I just merge it.
Thanks wizard!