Used cache does not get set early enough

[Oddant1]

When running an action with --use-cache (currently only pipelines but #332 may change this) we will call convert on all QIIME2Type args before we parse out the used cache. This will end up calling Archiver.load which will save a version of the inputs into the tmp cache's process pool. It may not be particularly possible or at least not easy to resolve this because the call to convert is a part of click.

[Oddant1]

closed by #332