1026501: Preserve PKI directories and have rpm own them.

Merged duplicated cert directory cleanup code into one method.

/etc/pki/consumer and /etc/pki/entitlement will now be preserved when you
unregister or clean.

We now remove just the identity cert and key as their filenames are known.

For entitlement directory we remove any files ending with .pem.

subscription-manager rpm will now create and own these directories on
installation.

File monitoring code needs no modifications as we check mtime, which adjusts on
any file addition/removal within the directories.