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_echo.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"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"
 	"github.com/mattermost/mattermost-server/v5/shared/mlog"
@@ -41,7 +42,7 @@ func (*EchoProvider) GetCommand(a *app.App, T i18n.TranslateFunc) *model.Command
 	}
 }
 
-func (*EchoProvider) DoCommand(a *app.App, args *model.CommandArgs, message string) *model.CommandResponse {
+func (*EchoProvider) DoCommand(a *app.App, c *request.Context, args *model.CommandArgs, message string) *model.CommandResponse {
 	if message == "" {
 		return &model.CommandResponse{Text: args.T("api.command_echo.message.app_error"), ResponseType: model.COMMAND_RESPONSE_TYPE_EPHEMERAL}
 	}
@@ -89,7 +90,7 @@ func (*EchoProvider) DoCommand(a *app.App, args *model.CommandArgs, message stri
 
 		time.Sleep(time.Duration(delay) * time.Second)
 
-		if _, err := a.CreatePostMissingChannel(post, true); err != nil {
+		if _, err := a.CreatePostMissingChannel(c, post, true); err != nil {
 			mlog.Error("Unable to create /echo post.", mlog.Err(err))
 		}
 	})