src/common/options: add config option for availability score

src/common/options: add config option for availability score

This commit modifies src/common/options/mon.yaml.in to add a
new config option to enable/disable tracking availability
score. This config option can be modified dynamically at
runtime as well.

To enable tracking availability score, we can run the
following command:

  ceph config set mon enable_availability_tracking true

By default, tracking availability score is enabled.

To disable tracking availability score:

  ceph config set mon enable_availablity_tracking false

When the feature is turned off, invoking the
`availability-status` command will display an error, prompting
the user to turn on the feature using the config option.

Fixes: https://tracker.ceph.com/issues/71494
Signed-off-by: Shraddha Agrawal <shraddhaag@ibm.com>