dockerfile: fix copying identity file
dockerfile: fix copying identity file

The identity file is copied into ~/.ssh but ~/.ssh may not exist.  Fix that
with mkdir -p.

If not using an identity file supplied via ansible, in addition, we should
not regenerate it on every deployment; test for id_rsa before creating a
new key pair.

Reported-by: Davide Caratti <44f6b86a4f44f713d97ccb1325316b79af6bdedb@redhat.com>
Signed-off-by: Paolo Bonzini <69d3ebcf5ee4e7f05a50dc23cd96655b730804b4@redhat.com>

patchew-project/patchew,patchew-project/patchew,patchew-project/patchew,patchew-project/patchew