Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/platform/services/upgrader/errors.go

@@ -0,0 +1,51 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package upgrader
+
+import (
+	"fmt"
+)
+
+// InvalidArch indicates that the current operating system or cpu architecture doesn't support upgrades
+type InvalidArch struct{}
+
+func NewInvalidArch() *InvalidArch {
+	return &InvalidArch{}
+}
+
+func (e *InvalidArch) Error() string {
+	return "invalid operating system or processor architecture"
+}
+
+// InvalidSignature indicates that the downloaded file doesn't have a valid signature.
+type InvalidSignature struct{}
+
+func NewInvalidSignature() *InvalidSignature {
+	return &InvalidSignature{}
+}
+
+func (e *InvalidSignature) Error() string {
+	return "invalid file signature"
+}
+
+// InvalidPermissions indicates that the file permissions doesn't allow to upgrade
+type InvalidPermissions struct {
+	ErrType            string
+	Path               string
+	FileUsername       string
+	MattermostUsername string
+}
+
+func NewInvalidPermissions(errType string, path string, mattermostUsername string, fileUsername string) *InvalidPermissions {
+	return &InvalidPermissions{
+		ErrType:            errType,
+		Path:               path,
+		FileUsername:       fileUsername,
+		MattermostUsername: mattermostUsername,
+	}
+}
+
+func (e *InvalidPermissions) Error() string {
+	return fmt.Sprintf("the user %s is unable to update the %s file", e.MattermostUsername, e.Path)
+}