For example, this allows you to do something like
`TelnetServer -c /usr/bin/nyancat` to have the TelnetServer run
`/usr/bin/nyancat` instead of `/bin/Shell`.
The C_OBJECT macro now also inserts a static construct(...) helper into
the class. Now we can make the constructor(s) private and instead call:
auto socket = CTCPSocket::construct(arguments);
construct() returns an ObjectPtr<T>, which we'll later switch to being
a NonnullRefPtr<T>, once everything else in in place for ref-counting.
