New CLI for install and config

[carlisia]

Specs: https://github.com/vmware-tanzu/velero/blob/master/design/cli-install-changes.md

v1.5

• 2Add a column to indicate the BSL status on velero backup-location get - Add a column to indicate the BSL status on velero backup-location get #2489
• Go over all flags and document what is optional, what is required, and default values. Capitalize all help messages - Go over all flags and document what is optional, what is required, and default values. Capitalize all help messages #2422
• Improve the velero backup-location command - Improve the velero backup-location command #2425
• Improve the velero snapshot-location command - Improve the velero snapshot-location command #2426

v1.6

• Rename "provider" to "location-plugin" - Rename "provider" to "location-plugin" #2420
• Add columns to BSL/VSL to indicate which one is the default - Add columns to backup storage location to indicate which one is the default #2421
• Add velero config server command - Add velero config server command #2423
• Add velero config restic command - Add velero config restic command #2424
• Improve the velero plugin command - Improve the velero plugin command #2427
• Add --dry-run flag to the new install and config commands - Add --dry-run flag to the new install and config commands #2432
• Have the BSL controller continuously update the server status based on the state of the BSLs - Have the BSL controller continuously update the server status based on the state of the BSLs #2488
• Add a velero status command to report if the server is ready to create backup or not - Add a velero status command to report if the server is ready to create backup or not #979