Provide a solution that does not create digests for origin.psdor files

[Archie-Miller]

The solution does provide a mechanism for picking the parts that can be signed (ISignatureBuilderPreset), and a mechanism for removing parts, the Sign will always add origin.psdor and origin.psdor.rels.

There is a need to ensure that these files are not included in the signature, hence the pull request.

No tests have been provided, as test seems to be quite challenging to create.

This is a minor change, so no issue has been created.