Add package registry quota limits (#21584)

Related #20471

This PR adds global quota limits for the package registry. Settings for
individual users/orgs can be added in a seperate PR using the settings
table.

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/setting/packages_test.go

@@ -0,0 +1,31 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package setting
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	ini "gopkg.in/ini.v1"
+)
+
+func TestMustBytes(t *testing.T) {
+	test := func(value string) int64 {
+		sec, _ := ini.Empty().NewSection("test")
+		sec.NewKey("VALUE", value)
+
+		return mustBytes(sec, "VALUE")
+	}
+
+	assert.EqualValues(t, -1, test(""))
+	assert.EqualValues(t, -1, test("-1"))
+	assert.EqualValues(t, 0, test("0"))
+	assert.EqualValues(t, 1, test("1"))
+	assert.EqualValues(t, 10000, test("10000"))
+	assert.EqualValues(t, 1000000, test("1 mb"))
+	assert.EqualValues(t, 1048576, test("1mib"))
+	assert.EqualValues(t, 1782579, test("1.7mib"))
+	assert.EqualValues(t, -1, test("1 yib")) // too large
+}