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

[larrybabb]

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.

[korikuzma]

@larrybabb I'm wondering if some of these would be useful to have in the VRS validation tests.