[Feature Request] Include server name in 2FA TOTP issuer

[lsago]

Problem description

If a user accesses multiple vantage6 instances with two-factor authentication, the identifier for each TOTP code on their phone may look the same. It's always vantage6 (cotopaxi): username, so there's no easy way to distinguish the different servers unless they are running different major versions or the user has different usernames.

Desired solution
A way for the server administrator to give human identifiable name to the server that is used in the issuer for the TOTP. For example, something like: vantage6 (server_name): username, instead of the version.

Additional context
Some TOTP do allow you to change part of that string at least, but that implies the user should take an extra step.

[bartvanb]

I guess it would make most sense to include a server_name as configuration option. I think we can put that information into the QR code easily. Alternatively, there is already the name configuration option that can be used directly, but that may not be a nice value always. Third option is to create a configuration option specifically for this in the mfa part of the configuration - but I don't think I prefer that.