Geometry Test Updates

This pull request fixes several issues with inheritance for RevitNodesTests. Some of these tests were using a test base class which did not start the HostFactory. As such, they were throwing LibG errors. By settings the ASM version to 220 and ensuring that these tests have the proper base class, the HostFactory is started and references the correct version of ASM and these tests pass.

This pull request also aligns with updates to the Revit Test Framework to allow running multiple tests in one session of Revit. In order to allow that, the HostFactory shutdown has been disabled. I need advice from @Randy-Ma and @pboyer on whether this is ok to do. The issue was that when running multiple tests within the same Revit session the shutdown call was happening after the first test run and subsequent tests could not restart the HostFactory.

This PR also refactors the ASM preloading methods earlier provided by @hlp. These refactorings generalize the methods so that they are not trying to look for all versions of ASM inside one method.

There are probably additional tests for which this inheritance needs to be updated. 

When this PR is merged, I will bring a subset of these changes into master, and make the appropriate changes, switching out 220 for 219, etc.

@Randy-Ma @pboyer PTAL.
@ikeough 
In the case that it is running from RTF, the AsmPreloader may get an invalid path.