On failure to unmarshal msgraph API error, log whole response body

[mickmister]

Summary

For context, please see https://community.mattermost.com/core/pl/a7m4w3tbufgzdj1trqkt3mj3tw

Here is the error we're currently getting when trying to create a superuser token for the status sync feature:

Error during user status sync job. err=not able to filter the super user client: msgraph GetSuperuserToken: status: 400 Bad Request: json: cannot unmarshal string into Go struct field ErrorResponse.error of type msgraph.ErrorObject

We're receiving a 400 Bad Request from Microsoft's API, with a response body that does not match the expected ErrorObject struct. Since the Unmarshal fails, we don't have any other context for what actual error occurred.

This PR makes it so we log the response body in the case that this unmarshal fails.

---

This error is originally happening here on line 99:

mattermost-plugin-mscalendar/server/remote/msgraph/call.go

Lines 96 to 104 in 8601bf2

	errResp := msgraph.ErrorResponse{Response: resp}
	err = json.Unmarshal(responseData, &errResp)
	if err != nil {
	return responseData, errors.WithMessagef(err, "status: %s", resp.Status)
	}
	if err != nil {
	return responseData, err
	}
	return responseData, &errResp

Ticket Link

https://mattermost.atlassian.net/browse/MM-52156