Allow everyone to read or write a wiki by a repo unit setting (#30495)

Replace #6312
Help #5833
Wiki solution for #639

models/migrations/v1_23/v297.go

@@ -0,0 +1,17 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_23 //nolint
+
+import (
+	"code.gitea.io/gitea/models/perm"
+
+	"xorm.io/xorm"
+)
+
+func AddRepoUnitEveryoneAccessMode(x *xorm.Engine) error {
+	type RepoUnit struct { //revive:disable-line:exported
+		EveryoneAccessMode perm.AccessMode `xorm:"NOT NULL DEFAULT 0"`
+	}
+	return x.Sync(&RepoUnit{})
+}