Add out-of-bounds check for memset and memcpy

[mrstanb]

This PR adds a check for the count and n parameter of memset and memcpy

• base should now be able to warn in case count or n is bigger than the smallest memory, pointed-to by dest
• Added a regession test case for this as well

[michael-schwarz]

I think there's still quite a few kinks to be ironed out, just let me know if any of my comments are cryptic or unclear!

[mrstanb]

Hopefully all remarks are now fixed. I also migrated the memset/memcpy checks completely from base to memOutOfBounds for consistency's sake. Feel free to review :)

[michael-schwarz]

Should be good to go after adding back the one TODO I commented on.