Added a new method to validate the GitHub API URL

[recena]

@reviewbybees specially, @oleg-nenashev

[ghost]

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[oleg-nenashev]

Hm... PR builder is dead

[recena]

@oleg-nenashev AFAIK, the test suite require local configuration. Was there a PR Builder configured in this repo?

[oleg-nenashev]

Yep. It has been configured on Kohsuke's beescloud account. I'm looking for it

[KostyaSha]

Unrelated to commit feature change.

[recena]

Indeed, I'll wait to know the maintainer's opinion.

[KostyaSha]

Never mix 2 unrelated changes in one when it possible. FB absolutely not related to Added a new method to validate the GitHub API URL

[oleg-nenashev]

I agree with @KostyaSha

[recena]

@oleg-nenashev @KostyaSha I agree. I'll change it.

[kohsuke]

I have a mixed feeling about adding more connectXyz methods, but it is indeed convenient to have some of them. Given that @recena feels strongly about having this particular convenience method, I think it's OK to have it.

I've massaged this PR somewhat by the following commit.

[recena]

@kohsuke Thanks for your time. I left GHApiInfo in a public class because we can need adding more fields in the future. I used isApiUrlValid() because we had isCredentialValid(), I tried to follow the rules.