feat(remote): add a command to clear the cache

[vmaerten]

I've added a command to clear the cache for remote files.

I've made the choice to disallow using download and clear-cache at the same time because clear-cache should be used as standalone.

We could allow using both flags at the same time, but we need to define the bahavior :

• Clear cache override download (so we clear the cache but not download)
• Download override clear cache (so we download but not clear cache)