Add owner attribute for reading public repos

[Nmishin]

Resolves #1938

The main idea here that we need to calculate owner parameter no matter this is anonymous user or user with token.

Before the change?

• No owner added if no token specified. Neither via GITHUB_OWNER env variable, neither via specifying owner in the provider configuration.
• Because of this path to repos calculated wrongly, for example like: /repos//some_public_repository/git/ref/heads/main

After the change?

• Owner can be added if no token used. Works via GITHUB_OWNER env variable and also in the provider configuration.
• All configuration precedence works as described in provider configuration docks.

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes
• No

---

[kfcampbell]

@Nmishin have you looked at #1029? What do you think about that approach vs. yours?

[Nmishin]

@kfcampbell I didn't saw it, honestly :)
My idea was exactly the same, I think we need to merge your MR

[kfcampbell]

@Nmishin I've done so now and will release it with the next version of the provider. Thank you for your help and contributions!