[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/manual_testing.go

@@ -4,6 +4,7 @@
 package manualtesting
 
 import (
+	"context"
 	"errors"
 	"hash/fnv"
 	"math/rand"
@@ -107,7 +108,7 @@ func manualTest(c *web.Context, w http.ResponseWriter, r *http.Request) {
 			Nickname: username[0],
 			Password: slashcommands.UserPassword}
 
-		user, _, err = client.CreateUser(user)
+		user, _, err = client.CreateUser(context.Background(), user)
 		if err != nil {
 			var appErr *model.AppError
 			ok = errors.As(err, &appErr)
@@ -126,7 +127,7 @@ func manualTest(c *web.Context, w http.ResponseWriter, r *http.Request) {
 		userID = user.Id
 
 		// Login as user to generate auth token
-		_, _, err = client.LoginById(user.Id, slashcommands.UserPassword)
+		_, _, err = client.LoginById(context.Background(), user.Id, slashcommands.UserPassword)
 		if err != nil {
 			var appErr *model.AppError
 			ok = errors.As(err, &appErr)

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 {