Support AWS Placement Group Partition Number in upstream CAPA.

Based on RFE-2194, support for pre-created Placement Groups was added in OCP. Following that, it is requested also to have the ability to specify the Partition Number of the Placement Group as this allows more precise allocation.

Scope

• The scope of this Epic is only to support this feature upstream. It is not scoped to support/update MAPI. 
• Placement Group (and Partition) will be pre-created by the user. User should be able to specify Partition Number along with PlacementGroupName on EC2 level to improve availability.

References

• https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html
• https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_Placement.html
• https://github.com/kubernetes-sigs/cluster-api-provider-aws/pull/4273

Acceptance Criteria:

• Add a feature in the upstream to support partition number.