Migrate to stateless app.App (#17542)

* add request context

* move initialialization to server

* use app interface instead of global app functions

* remove app context from webconn

* cleanup

* remove duplicated services

* move context to separate package

* remove finalize init method and move content to NewServer function

* restart workers and schedulers after adding license for tests

* reflect review comments

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/plugin_context.go

@@ -2,18 +2,3 @@
 // See LICENSE.txt for license information.
 
 package app
-
-import (
-	"github.com/mattermost/mattermost-server/v5/plugin"
-)
-
-func (a *App) PluginContext() *plugin.Context {
-	context := &plugin.Context{
-		RequestId:      a.RequestId(),
-		SessionId:      a.Session().Id,
-		IpAddress:      a.IpAddress(),
-		AcceptLanguage: a.AcceptLanguage(),
-		UserAgent:      a.UserAgent(),
-	}
-	return context
-}