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/slashcommands/command_me.go

@@ -5,6 +5,7 @@ package slashcommands
 
 import (
 	"github.com/mattermost/mattermost-server/v5/app"
+	"github.com/mattermost/mattermost-server/v5/app/request"
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/shared/i18n"
 )
@@ -34,7 +35,7 @@ func (*MeProvider) GetCommand(a *app.App, T i18n.TranslateFunc) *model.Command {
 	}
 }
 
-func (*MeProvider) DoCommand(a *app.App, args *model.CommandArgs, message string) *model.CommandResponse {
+func (*MeProvider) DoCommand(a *app.App, c *request.Context, args *model.CommandArgs, message string) *model.CommandResponse {
 	return &model.CommandResponse{
 		ResponseType: model.COMMAND_RESPONSE_TYPE_IN_CHANNEL,
 		Type:         model.POST_ME,