Change --nocache flag to be a hidden option

[tpill90]

The --nocache flag is a common point of confusion as it's naming is very similar to Lancache. It also implies that it should not use the Lancache server itself, when in reality it will not use the manifests cached on disk.

Under normal usage the --nocache flag isn't necessary for users, its more of a useful debugging flag for myself. This issue is going to change the flag over to being a hidden flag, so that it can continue to be used by users who are already using it without issue.

[tpill90]

Released in v2.4.0