feat: Allow customizing the display name of the OpenID Connect provider

[thefinn93]

Normal users probably don't know what "OpenID Connect" means and they probably shouldn't need to. They know the name of the account provider, so allow the miniflux admin to specify that and show it to the user instead of the string "OpenID Connect". By default, the name is "OpenID Connect" which means this doesn't change the default behavior (except with German locale, discussed below).

I tested this by deploying it to my own instance, where it seems to work as expected.

Outstanding issues that I haven't figured out the best way to address:

• hi_IN locale doesn't use the string "OpenID Connect" or anything that looks like it. Not sure what the best way to approach this is, open to suggestions.
• de_DE locale referred to it as OpenID-Connect, this change will drop the - from the default resulting in the string being set to OpenID Connect. This feels easy enough to special case the default for if it's a problem.

Do you follow the guidelines?

• I have tested my changes
• There is no breaking changes
• I really tested my changes and there is no regression
• Ideally, my commit messages follow the Conventional Commits specification
• I read this document: https://miniflux.app/faq.html#pull-request

[fguillot]

• hi_IN locale doesn't use the string "OpenID Connect" or anything that looks like it. Not sure what the best way to approach this is, open to suggestions.

hi_IN currently shows %!(EXTRA string=xxx). To keep things simple, perhaps the provider name could be between parentheses: "page.settings.link_oidc_account": "मेरा ओपन-ईद खाता जोरीय (%s)",. Native speakers may have a better way to reword the translated text.