Add Certificate Signing Tasks #90

We need to:

1. Sign the module and manifest files.
2. Create a FileCatalog (via New-FileCatalog)
3. Sign the File catalog

We should be able to enable/disable via properties. It would be good to make it flexible to allow different type of commonly found certificates/signing processes.

Reference: https://p0w3rsh3ll.wordpress.com/2017/09/19/psgallery-and-catalog-files/