adding a check for loading resource files before all partial integration tests begin. Allows the user to spot if they have not set their working dir correctly

moving the class setup function to half-fat tests, so the TEST_OUT variable is reset for the half-fat tests but not the full-fat ones when being loaded by unittest.main

changing tests to check for success via the TestResult object and changing the exit code - previously failing tests were not  being picked up by the gitlab runner

reseting the IntegrationTestUtils.TEST_OUT_PATH variable upon loading each test class, was having its value carried across from previous test runs when being run as past of a test suite

This reverts commit 8c32ad24

some additional comments and code-tidying