Add Debian package registry (#24426)

Co-authored-by: @awkwardbunny

This PR adds a Debian package registry.
You can follow [this
tutorial](https://www.baeldung.com/linux/create-debian-package) to build
a *.deb package for testing.
Source packages are not supported at the moment and I did not find
documentation of the architecture "all" and how these packages should be
treated.


![grafik](https://user-images.githubusercontent.com/1666336/218126879-eb80a866-775c-4c8e-8529-5797203a64e6.png)

Part of #20751.

Revised copy of #22854.

---------

Co-authored-by: Brian Hong <brian@hongs.me>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Giteabot <teabot@gitea.io>

models/migrations/v1_20/v256.go

@@ -0,0 +1,23 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_20 //nolint
+
+import (
+	"xorm.io/xorm"
+)
+
+func AddIsInternalColumnToPackage(x *xorm.Engine) error {
+	type Package struct {
+		ID               int64  `xorm:"pk autoincr"`
+		OwnerID          int64  `xorm:"UNIQUE(s) INDEX NOT NULL"`
+		RepoID           int64  `xorm:"INDEX"`
+		Type             string `xorm:"UNIQUE(s) INDEX NOT NULL"`
+		Name             string `xorm:"NOT NULL"`
+		LowerName        string `xorm:"UNIQUE(s) INDEX NOT NULL"`
+		SemverCompatible bool   `xorm:"NOT NULL DEFAULT false"`
+		IsInternal       bool   `xorm:"NOT NULL DEFAULT false"`
+	}
+
+	return x.Sync(new(Package))
+}