Since the API already disallows this, this makes the error cleaner and
more explicit when a user is trying to start/ssh into a codespace that
has a pending operation.
Example of the old error message:
```
$ gh cs ssh -c cwndrws-redacted
Starting codespace ⣽error connecting to codespace: error starting codespace: HTTP 422: your codespace has an operation pending: updating to a sku with a different amount of storage; please wait until this operation is complete (https://api.github.com/user/codespaces/cwndrws-redacted/start)
exit status 1
```
Example of the new error message:
```
$ gh cs ssh -c cwndrws-redacted
codespace is disabled while it has a pending operation: Changing machine types...
exit status 1
```
afa71c4b2f