Automated date based cleanup option for mirrored artifacts

[dzikoysk]

Initially requested for Reposilite 4.x by @solonovamax:

with this, you'd also be able to provide the following things:

add a badge on remote artifacts/modules to indicate they're from a mirror (& maybe which mirror they're from?)
allow administrators to set storage limits on mirrored artifacts and use smth like an LRU policy to discard old cached artifacts.

~ #2005 (comment)

[solonovamax]

I think it's also important to highlight this part (ie. this feature depends on adding the ability to set the storage to an external location, as it'd make it quite a lot easier to measure the size of all artifacts cached from a mirrored repo)

smth I thought of a while back that would be nice is: the ability to store cached files from a proxied/mirrored repository in a separate location.

so, for example, the contents of the releases (that have been uploaded directly to the repo) repo could be stored in repo/releases.
but then, say you're mirroring foo.com and bar.net (and reposilite is configured to store those artifacts)
then, the artifacts from each of those would be located in smth like mirrors/releases/foo.com and mirrors/releases/bar.net.