Saptune gatherer

[rtorrero]

This PR adds a new Saptune gatherer using the same saptune core code as the #253 (saptune_discovery). The whitelisted saptune arguments are the following:

var whitelistedArguments = map[string][]string{
	"status":          {"status", "--non-compliance-check"},
	"solution-verify": {"solution", "verify"},
	"solution-list":   {"solution", "list"},
	"note-verify":     {"note", "verify"},
	"note-list":       {"note", "list"},
}

[arbulu89]

@rtorrero Some few things.
Besides that, i don't still see any "caching" system.
I mean, we must only run the commands for each argument once, so you need to check if they were executed, and store the output

[arbulu89]

Just for purity we could remove this first empty line

[rtorrero]

I added it because I noticed the output of saptune adds it, but it shouldn't make any difference

[arbulu89]

Good!
Once we have this minor things fixed we are ready to merge.
You can start working in the documentation of the gatherer in wanda if you want

[arbulu89]

Thank you @rtorrero
Ready to merge from my side.
PD: added last nitpick comment if you want to have a look 🙈

[arbulu89]

We could return nil, &SaptuneNotInstalled as well (the same for the next)
And even SaptuneNotInstalled.Wrap(err.Error()) in this case, as we have the rpm command error