Clean up WebAuthn javascript code and remove JQuery code (#22697)

There were several issues with the WebAuthn registration and testing
code and the style
was very old javascript with jquery callbacks.

This PR uses async and fetch to replace the JQuery code.

Ref #22651

Signed-off-by: Andrew Thornton <art27@cantab.net>

---------

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: silverwind <me@silverwind.io>

routers/web/user/setting/security/webauthn.go

@@ -6,6 +6,8 @@ package security
 import (
 	"errors"
 	"net/http"
+	"strconv"
+	"time"
 
 	"code.gitea.io/gitea/models/auth"
 	wa "code.gitea.io/gitea/modules/auth/webauthn"
@@ -23,8 +25,8 @@ import (
 func WebAuthnRegister(ctx *context.Context) {
 	form := web.GetForm(ctx).(*forms.WebauthnRegistrationForm)
 	if form.Name == "" {
-		ctx.Error(http.StatusConflict)
-		return
+		// Set name to the hexadecimal of the current time
+		form.Name = strconv.FormatInt(time.Now().UnixNano(), 16)
 	}
 
 	cred, err := auth.GetWebAuthnCredentialByName(ctx.Doer.ID, form.Name)