Erroneous error handling in http admin

[pnoltes]

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