feature-request: add installation of VPA as default component to sow

[HerrmannHinz]

What would you like to be added: install vertical pod autoscaler per default via sow

Why is this needed: https://github.com/gardener/garden-setup/pull/286

if the VPA and its crds is not installed ppl wont be able to install gardener via sow deploy. see the above PR.

also see the following slack msges: https://kubernetes.slack.com/archives/CB57N0BFG/p1599656625060400