[MM-37557] Move error out of client4 response (#18101)

* Return an error seperately from Response

* Remove BuildErrorResponse

* Drop Response.Error from model/client4.go

* Migrate require.Nil checks

* Migrate require.NotNil checks

* More manual fixes

* Move error check out of CheckOKStatus and CheckCreatedStatus

* Move error check out of CheckForbiddenStatus

* Move error check out of CheckUnauthorizedStatus

* Move error check out of CheckNotFoundStatus

* Move error check out of CheckBadRequestStatus

* Move error check out of CheckNotImplementedStatus and CheckRequestEntityTooLargeStatus

* Move error check out of CheckInternalErrorStatus

* Move error check out of CheckServiceUnavailableStatus

* Remove error check from checkHTTPStatus

* Remove remaining references to Response.Error

* Check previously unchecked errors

* Manually fix compile and linter errors

* Return error in CreateWebSocket methods

* Return error instead of *AppError in DoApi methods

* Manually fix bad replacments

* Conistently return Response and error

* Use err instead of seperate bool return value to indicate success

* Reduce ussage of model.AppError in web/oauth_test.go

* Remove client4.Must

* Check error in buf.ReadFrom

* Fix failing tests

api4/data_retention_test.go

@@ -5,12 +5,15 @@ package api4
 
 import (
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestDataRetentionGetPolicy(t *testing.T) {
 	th := Setup(t)
 	defer th.TearDown()
 
-	_, resp := th.Client.GetDataRetentionPolicy()
+	_, resp, err := th.Client.GetDataRetentionPolicy()
+	require.Error(t, err)
 	CheckNotImplementedStatus(t, resp)
 }