[WIP] Implement more v3 endpoints

[terwey]

See #426 for task tracking

This PR contains:

• /api/clusters/{clusterName}/services/actions/provision
• /api/clusters/{clusterName}/services/actions/unprovision
• /api/clusters/{clusterName}/schema/{schemaName}/{tableName}/actions/checksum-table
• /api/clusters/{clusterName}/schema/{schemaName}/{tableName}/actions/move-table/{clusterShard}
• /api/clusters/{clusterName}/schema/{schemaName}/{tableName}/actions/reshard-table
• /api/clusters/{clusterName}/schema/{schemaName}/{tableName}/actions/reshard-table/{clusterList}
• /api/clusters/{clusterName}/schema/{schemaName}/{tableName}/actions/universal-table
• /api/clusters/{clusterName}/shardclusters

CLI Changes:

• show command
• status command