Add ability to specify custom names in the OAuth login buttons

[crapStone]

closes #154

Explanation why I chose that path is also in that issue.

[alyssadev]

I would also suggest this change I've made on my own instance 7e5d427

[thomiceli]

Throwing a random idea : use the domain name of the instance to get the name instead of a new config

[alyssadev]

Perhaps this could be fetched automatically with the option to override. Any html page on a Gitea-compatible instance should have a meta property tag for og:site_name, i imagine we'd want to parse out the "Git with a cup of tea" thing that seems to be present unless explicitly removed, as in the Gitea instance I have my opengist instance connected to.

<meta property="og:site_name" content="TWS Gitea: Git with a cup of tea">

[crapStone]

I would also suggest this change I've made on my own instance 7e5d427

I talked with a friend about that page, but it dind't cross my mind to add the new config fields there 😆

[crapStone]

Throwing a random idea : use the domain name of the instance to get the name instead of a new config

I'm evaluating this service for Codeberg (see here) and just using codeberg.org isn't enough, because we are not just another Forgejo/Gitea instance.

I could add a check after the parsing of the config and if no custom name is set the name will be set to the domain name.

[jolheiser]

fwiw I think this impl is fine. A domain check seems like it may be overcomplicating it when an override exists.

[thomiceli]

Thank you for the contributions :)