Review the logging of cta-rmcd

Problem

Currently, the log format of cta-rmcd looks like this:

05/23 01:59:39  1647 rmc_srv_unmount: RMC92 - unmount request by 1000,33 from localhost
05/23 01:59:39  1647 rmc_srv_unmount: RMC98 - unmount L83553 1 0
05/23 01:59:42  1647 rmc_srv_unmount: returns 0
05/23 01:59:46  1647 rmc_srv_mount: RMC92 - mount request by 1000,33 from localhost
05/23 01:59:46  1647 rmc_srv_mount: RMC98 - mount L91615/0 on drive 1
05/23 02:00:15  1647 rmc_srv_mount: returns 0

This is a legacy format from CASTOR era.

It should be changed to follow the same format / logic as is used elsewhere in the CTA project (cta-frontend, cta-taped).

Idealy same time format, JSON format, key values.

Please keep in mind that while this log file is not used anywhere in the operations (other than just checking whether mount/unmount worked), those messages are parsed to cta-taped daemon.

Objective

• Turn the rmcd logs to JSON.
• As shown in #704 (closed), these logs need to be properly ingested by the cta-taped service and merged into its logs without breaking the ingestion of those logs by the monitoring infrastructure.