feat: consider WebAuthn & SSH for instance signing (#7693)

- Currently the options `pubkey` and `twofa` only consider TOTP and GPG keys respectively. Adjust the code to also consider WebAuthn credentials and SSH keys.
- While adding the new unified functions I noticed that certain places also benefited from using these unified functions and took the liberty (where it was either a trivial translation or it was covered under testing) to use the new unified functions.
- Resolves forgejo/forgejo#7658
- Adds unit and integration tests.

Documentation PR: https://codeberg.org/forgejo/docs/pulls/1166

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7693
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

routers/web/admin/users.go

@@ -248,17 +248,12 @@ func prepareUserInfo(ctx *context.Context) *user_model.User {
 	}
 	ctx.Data["Sources"] = sources
 
-	hasTOTP, err := auth.HasTwoFactorByUID(ctx, u.ID)
+	hasTwoFactor, err := auth.HasTwoFactorByUID(ctx, u.ID)
 	if err != nil {
-		ctx.ServerError("auth.HasTwoFactorByUID", err)
+		ctx.ServerError("HasTwoFactorByUID", err)
 		return nil
 	}
-	hasWebAuthn, err := auth.HasWebAuthnRegistrationsByUID(ctx, u.ID)
-	if err != nil {
-		ctx.ServerError("auth.HasWebAuthnRegistrationsByUID", err)
-		return nil
-	}
-	ctx.Data["TwoFactorEnabled"] = hasTOTP || hasWebAuthn
+	ctx.Data["TwoFactorEnabled"] = hasTwoFactor
 
 	return u
 }