Enable Seperate CIDR for LB and Worker nodes definition in gardener

[hariprasath91]

How to categorize this issue?

/area networking
/kind enhancement
/platform openstack

We want to enable below enhancement where ,

1. Need to enable a seperate CIDR for LB for the shoot cluster.
2. Need to enable a seperate CIDR for nodes on the shoot
3. Enable possibility of enabling internal loadbalancer.
4. Enable the possibility of enabling external loadbalancer.

Why is this needed
We need this feature to isolate the access to the customer projects when the BGP VPN is enabled. We dont want to enable the access to entire cluster CIDR rather only to LB CIDR alone where the connections can be enabled,