Remove Compression from EncryptContentPGP and SignContentPGP

The first version of the EncryptContentPGP Processor set ZIP as the default value for the Compression Algorithm property, aligning the behavior of EncryptContent with PGP settings.

The refreshed specification for OpenPGP is still in progress, but one of the changes includes removal of compression.

For new messages created using EncryptContentPGP the Compression Algorithm property should be removed.

The Symmetric Key Algorithm property supports optional selection of Camellia cipher algorithms. This algorithm is uncommon and supported values should be dropped.

These changes will put EncryptContentPGP in a better position to support future OpenPGP specification revisions.

The DecryptContentPGP Processor determines compression and cipher algorithms based on message information, so these changes will not impact decryption.