support update, enable and disable backup policy

[posriniv]

bash-5.2$ ./ybm backup policy update --cluster-name=loving-squid --retention-period-in-days=2  --full-backup-frequency-in-days=10 
Successfully updated backup policy for cluster loving-squid

bash-5.2$ ./ybm backup policy list --cluster-name=loving-squid
Time Interval(days)   Days of the Week   Backup Start Time
10                    NA                 NA

bash-5.2$ ./ybm backup policy update --cluster-name=loving-squid --retention-period-in-days=2  --full-backup-schedule-days-of-week=th,fr,sa,su --full-backup-schedule-time=23:05
Successfully updated backup policy for cluster loving-squid

bash-5.2$ ./ybm backup policy list --cluster-name=loving-squid
Time Interval(days)   Days of the Week   Backup Start Time
NA                    Su,Th,Fr,Sa        23:05

bash-5.2$ ./ybm backup policy disable --cluster-name=loving-squid
Successfully disabled backup policy for cluster loving-squid

bash-5.2$ ./ybm backup policy list --cluster-name=loving-squid
A newer version is available. Please upgrade to the latest version v0.1.17
No backup policies found for the given cluster

bash-5.2$ ./ybm backup policy enable --cluster-name=loving-squid
Successfully enabled backup policy for cluster loving-squid

bash-5.2$ ./ybm backup policy list --cluster-name=loving-squid
Time Interval(days)   Days of the Week   Backup Start Time
NA                    Su,Th,Fr,Sa        23:05

This way, simple and custom backup policy can be configured through the CLI. Also, the policy can be either enabled or disabled. Relevant guards are put in place to restrict and guide the user to provide only the allowed set of flags.

[shinji62]

Adding some test will be welcome

[posriniv]

@shinji62 @cdavid please take another look