New configuration parameter updates URI for CRL Distribution points
inside Vault, to a publicly-accessible location. The purpose is not
to impact all users, so I did not add a global configuration
parameter. Instead, only 'upload_signed_csr' action was updated
with an optional parameter introduced named 'crl-distribution-point'.
Closes-bug: #2048237
Change-Id: I8dbfc0deb9f547100bb63bd6b20737734e97667b