Adds the auth methods 'name' field to the login buttons, if it differs from the auth type.

[nwaldispuehl]

This is supposed to improve the usability for non-IT corporate users:
We had a hard time* to convince our technically less inclined users that 'OIDC' in fact means our companys Keycloak SSO server. I always wished I could arbitrarily name the login buttons; hence this feature.

What do you think?

(* actually not really hard, but for the sake of the argument... 😬 )

---

Given this config file extract:

...
auth:
  ...
  oidc:
    # A name for the backend (is shown on the login page and possibly in the devices list of the 'all devices' admin page)
    name: "MyCompany SSO"
    ...

  gitlab:
    name: "MyCompany Gitlab"
    ...

the login screen previously looked like this:

and with this change would look like this:

To implicitly reproduce the old behavior one would need to set the name to the type:

  gitlab:
    name: "gitlab"

[mergeable]

Thanks for creating a pull request! A maintainer will review your changes shortly. Please don't be discouraged if it takes a while.

[GoliathLabs]

LGTM