Resolve "Add Backstage charts to BB umbrella repository"

Package Merge Request

Package Changes

Add Backstage to big bang chart

Package MR

big-bang/product/packages/backstage!63 (merged)

big-bang/product/packages/backstage!60 (merged)

For Issue

Closes #2303 (closed)

Closes big-bang/product/packages/backstage#50 (closed)

Closes big-bang/product/packages/backstage#13 (closed)

Upgrade Notices

New package - Beta - Backstage:

Backstage, the popular developer portal framework, is now available as a Beta release addon for big bang. It currently supports several core packages of big bang as an enabled component resource. This includes base bigbang kubernetes resources information, istio, kiali, monitoring, kyverno, and logging, with plans to include other core and addon packages in the near future as dynamic components for big bang users. See backstage package architecture for information on backstage within bigbang. See P1 backstage chart for details and documentation regarding backstage configuration.