c#: Update the allocation clean up code to avoid using closure which will allocate on the heap

[jsturtevant]

Also note that cleanups.Add(()=> NativeMemory.AlignedFree({address})); will allocate closure.

Agree. I would consider handling this in a stack allocated struct that implements IDisposable or a ref struct with a Dispose() method. Note that Roslyn allows a ref struct with a Dispose(), not implementing IDisposable, to be used in a using statement.

Originally posted by @AaronRobinsonMSFT in #1012