[MM-49989] Pass a context.Context to Client4 methods (#22922)

* Migrate all method in model/client4.go to accept a context.Context

* Fix th.*Client

* Fix remaining issues

* Empty commit to triger CI

* Fix test

* Add cancellation test

* Test that returned error is context.Canceled

* Fix bad merge

* Update mmctl code

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/manualtesting/test_autolink.go

@@ -4,6 +4,7 @@
 package manualtesting
 
 import (
+	"context"
 	"errors"
 	"net/http"
 
@@ -32,7 +33,7 @@ func testAutoLink(env TestEnvironment) *model.AppError {
 	post := &model.Post{
 		ChannelId: channelID,
 		Message:   linkPostText}
-	_, _, err := env.Client.CreatePost(post)
+	_, _, err := env.Client.CreatePost(context.Background(), post)
 
 	var appErr *model.AppError
 	if ok = errors.As(err, &appErr); !ok {