Fixes #7303 - Added content view version param to errata api

I noticed in https://github.com/Katello/katello/pull/4624/files#diff-2cdfba65666157bd141c8185888cdc9bR64 we will 'fail' if the version cannot be found; however, we do not here.  Should we be consistent, since these controllers (for packages and errata) are providing very similar function, but for different content?

This could apply for each of the 'find' methods.  I realize the inconsistency was not introduced by this PR, so can handle with separately, if needed.