Allow for creation of InstanceGroup for bootstrap instance #1265
Description
/kind feature
Describe the solution you'd like
Currently, when using CAPG for bootstrapping a cluster as part of openshift/enhancements#1528, the instance created for bootstrap is added to the first InstanceGoup along with another control plane machine. This causes problems when using an internal Load Balancer and interfacing with the Machine API, which expects the bootstrap Instance to be in a separate InstanceGroup. it would be useful to have to ability to create an InstanceGroup for bootstrap and add the bootstrap instance to it. This bootstrap InstanceGroup would be added to the list of backends that the Internal LoadBalancer's Backend Service uses.
By default this bootstrap InstanceGoup should not be created.
Anything else you would like to add:
When using a bootstrap Instance, the resulting list of InstanceGroups would look like this, with 1 instance in each group.
NAME LOCATION SCOPE NETWORK MANAGED INSTANCES
<id>-bootstrap us-east1-b zone <id>-network No 1
<id>-master-us-east1-b us-east1-b zone <id>-network No 1
<id>-master-us-east1-c us-east1-c zone <id>-network No 1
<id>-master-us-east1-d us-east1-d zone <id>-network No 1