Remove the `is_subproject` check in the meson build file. This would
conditionally create and handle config data generation and info based on
use as a subproject or not. This seemed to be a very poor and
non-standard approach using config data. Now, the parent project using
the library will pass parameters as part of `default_options` to the
subproject . Then the project always dumps its own config file rather
than being passed up and created by the parent project. This was also
modified and is reflected in the other xb-engine core libraries.