Improve "generate new access token" form (#33730)

Fix: https://github.com/go-gitea/gitea/issues/33519

As discussed in [PR
#33614](https://github.com/go-gitea/gitea/pull/33614), the
ScopedAccessTokenSelector Vue component is not particularly useful.

This PR removes the component and reverts to using HTML templates. It
also introduces some (hopefully) useful refactoring.

The Vue component was causing the UX bug reported in the linked issue.
Required form fields are now properly working, as expected (see
screenshot).

![Screenshot from 2025-02-25
22-00-28](https://github.com/user-attachments/assets/41167854-0718-48b0-a3ee-75ca3a7b8b20)

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/forms/user_form_test.go

@@ -4,10 +4,8 @@
 package forms
 
 import (
-	"strconv"
 	"testing"
 
-	auth_model "code.gitea.io/gitea/models/auth"
 	"code.gitea.io/gitea/modules/setting"
 
 	"github.com/gobwas/glob"
@@ -104,28 +102,3 @@ func TestRegisterForm_IsDomainAllowed_BlockedEmail(t *testing.T) {
 		assert.Equal(t, v.valid, form.IsEmailDomainAllowed())
 	}
 }
-
-func TestNewAccessTokenForm_GetScope(t *testing.T) {
-	tests := []struct {
-		form        NewAccessTokenForm
-		scope       auth_model.AccessTokenScope
-		expectedErr error
-	}{
-		{
-			form:  NewAccessTokenForm{Name: "test", Scope: []string{"read:repository"}},
-			scope: "read:repository",
-		},
-		{
-			form:  NewAccessTokenForm{Name: "test", Scope: []string{"read:repository", "write:user"}},
-			scope: "read:repository,write:user",
-		},
-	}
-
-	for i, test := range tests {
-		t.Run(strconv.Itoa(i), func(t *testing.T) {
-			scope, err := test.form.GetScope()
-			assert.Equal(t, test.expectedErr, err)
-			assert.Equal(t, test.scope, scope)
-		})
-	}
-}