Mithril mkdir in scripts for existing deployments

[TrevorBenson]

Both mithril-signer and mithril-client will check for directory existence before generating the mithril environment file. If the directory does not exist it will mkdir -p and chown -R.

[Scitz0]

Looks good

[TrevorBenson]

Small adjustment to ensure client creates directories even when POOL_NAME is still CHANGEME (for relays or syncing before pool has been created).

Testing

I tested under a RHEL 9 instance. First pass w/ guild-deploy.sh NOT using -s m creates the directories. I then rm -rf'd the ${CNODE_HOME}/mithril path, and used ${CNODE_HOME/scripts/mithril-client.sh -u and it pre-created the directories and set permissions prior to generating the env file. The generate function inside mithril-signer.sh also has the check and mkdir at the very beginning, so should handle it identically.