Erroneous error handling in http admin

There are several issues in the http admin error handling:

1. If `httpAdmin_create` finally fails here, an error code should be returned instead.
2. The above applies to `websocketAdmin_create`.
3. `httpAdmin_create` should take the responsibility of releasing `httpRoot` in error condition, which is currently not done.
4. In `http_admin_stop`, various resources is NOT released in reverse order as they are acquired.

Our new error injector may help testing this.

_Originally posted by @PengZheng in https://github.com/apache/celix/pull/476#discussion_r1111598092_