setup a list of unique variant examples for the basis of testing

For Allele, CNVCopy and CNVChange pull any *special* cases that will comprehensively exercise the vrs-python normalization processes.

@larrybabb should add this list to the tests directory and notify the developers when it is updated so test cases can be written

This should help avoid us missing any breaking changes to the the computed ids based on coding or model changes within a major release.