Support the new `stay_logged_in` field in login.

[dessalines]

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Describe The Feature Request Below

Support the new stay_logged_in field in login.

See LemmyNet/lemmy#6058

[MV-GH]

This doesn't make sense for Apps. It will be on by default.

[dessalines]

I agree. I think the login form will still need to send that field tho (just as always true for us), otherwise the jwt will expire in the back-end.