Check quality of existing release before getting a new one using cutoff unmet

[RaunoT]

Is your feature request related to a problem? Please describe.

Related to what I described in #162

To summarize - the way that Soularr currently works leads to the same releases being downloaded over and over again for no real benefit while using search_source = cutoff_unmet

Describe the solution you'd like:

Soularr should check for the existing quality of a release and compare it to the quality of the download it wants to get. If the existing quality is the same as the download, there is no point in downloading.

Describe alternatives you've considered:

Additional context:

[insanemal]

Awesome!
This will take a bit as it hinges on the search source and on what the Lidarr api provides

But thanks!