podman-etcd: code clean-up

Notes

• fixed a couple of places where $? was used instead of $rc
• use if is_standalone; instead of if [ $? -eq 0 ] and other functions (and made sure we use rc=$? for cases where rc is used more than once)

Changes

• use tabs for all indentation
• quote string values in if's
• move all helper functions before agent's start/stop/monitor/etc command functions
• move meta-data/usage|help actions before this section in separate case-statement
• removed promote/demote-actions from metadata/usage. can re-add later if we need them
• use NODENAME (ocf_local_nodename)/NODEIP instead of $THIS_*/$nodename variables
• add crictl to validate-all() binary-checks
• cleaned up logging to always have space between : and $var
• start() - retry-loop: use break
• uncommented #remove_container()-line in stop-action
• replace -a in if with && (there are some known issues with using -o/-a in special cases)
• podman_notify(): combine the start/stop in case statement