Integration with External Language Package Managers

[kuszewski]

The package will need to be able to install dependencies from third-party package managers. We can do that with running a system command today, but it'd be good to make this easy. For example, making it so that it's easy to run maven and install the dependencies in the packages directory (as suggested in an earlier story).

[isc-tleavitt]

FYI, here's some relevant work for node/npm: https://github.com/intersystems/isc-ipm-js