remove util.OptionalBool and related functions (#29513)

and migrate affected code

_last refactoring bits to replace **util.OptionalBool** with
**optional.Option[bool]**_

routers/api/v1/admin/hooks.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 
 	"code.gitea.io/gitea/models/webhook"
+	"code.gitea.io/gitea/modules/optional"
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/util"
@@ -37,7 +38,7 @@ func ListHooks(ctx *context.APIContext) {
 	//   "200":
 	//     "$ref": "#/responses/HookList"
 
-	sysHooks, err := webhook.GetSystemWebhooks(ctx, util.OptionalBoolNone)
+	sysHooks, err := webhook.GetSystemWebhooks(ctx, optional.None[bool]())
 	if err != nil {
 		ctx.Error(http.StatusInternalServerError, "GetSystemWebhooks", err)
 		return