Fix org contact email not clearable once set (#36975)

When the email field was submitted as empty in org settings (web and
API), the previous guard `if form.Email != ""` silently skipped the
update, making it impossible to remove a contact email after it was set.

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

services/forms/org.go

@@ -36,13 +36,13 @@ func (f *CreateOrgForm) Validate(req *http.Request, errs binding.Errors) binding
 
 // UpdateOrgSettingForm form for updating organization settings
 type UpdateOrgSettingForm struct {
-	FullName                  string `binding:"MaxSize(100)"`
-	Email                     string `binding:"MaxSize(255)"`
-	Description               string `binding:"MaxSize(255)"`
-	Website                   string `binding:"ValidUrl;MaxSize(255)"`
-	Location                  string `binding:"MaxSize(50)"`
-	MaxRepoCreation           int
-	RepoAdminChangeTeamAccess bool
+	FullName                  *string `binding:"MaxSize(100)"`
+	Email                     *string `binding:"MaxSize(255)"`
+	Description               *string `binding:"MaxSize(255)"`
+	Website                   *string `binding:"ValidUrl;MaxSize(255)"`
+	Location                  *string `binding:"MaxSize(50)"`
+	MaxRepoCreation           *int
+	RepoAdminChangeTeamAccess *bool
 }
 
 // Validate validates the fields