Add ability to limit non-admin users to a single auth method

[ant385525]

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Please provide a concise description of the problem that would be addressed by this feature.

Currently if a user is created using the default "mealie" auth method then another auth method is added there is no way to limit the user to the secondary method.
There is an option in the settings "Authentication Method" but it's only used if a user is created via OIDC, not originally created through Mealie.

Please provide a concise description of the feature that would resolve your issue.

Change the logic of the Authentication Method setting to apply even if a user is created through Mealie. Admins would be able to limit users to a single auth method easily.

Please consider and list out some caveats or tradeoffs made in your design decision

This would change the current logic of the setting so an "all" option should also be added which would be the default behavior. Also IMO admins should not be able to change this for themselves, there should always be the default auth as a fallback for admins.

Additional Information

• If this is accepted I'm willing to submit a PR to provide this feature
• If this is accepted I'm willing to help maintain this feature
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