Add OSKAR compilation step to CI/CD

In order to complete https://jira.skatelescope.org/browse/AST-39, OSKAR needs to be compiled within CI/CD (https://jira.skatelescope.org/browse/AST-87) so as to enable automated testing later on.

OSKAR can be cloned from https://github.com/OxfordSKA/OSKAR/tree/master/python