Warn about (de)compressing zip/7z only if there's reason to assume it'd take up a considerable amount of RAM

[vrmiguel]

Creating this ticket for discussion. I feel like it's only worthwhile to ask the user about this if ouch estimates that a worrying amount of RAM will be taken up.

E.g. if the user's in a 16GB system, and tries to decompress a 2MB .zip, then they wouldn't particularly care about ouch having a max RSS of 10MB or so in this case.

In a 4GB system, decompressing a 4GB .7z file, then sure, it makes sense to prompt the user.