Add an option to pin memory for virtual machine

[maximsnezhkov]

/kind feature

Describe the solution you'd like
As an operator I would like to pin memory to max for workload clusters running at production environment.
Memory reservation management via the flag will allow operator to override the value of the virtual machine template for test environments in which there may be limited memory resources. As an operator, I will be able to opt out of different build scenarios for test and production environments.

Anything else you would like to add:
Option has already available by vsphere api.

Environment:

• Cluster-api-provider-vsphere version: v1.6.0
• Kubernetes version: (use kubectl version): v1.22.17
• OS (e.g. from /etc/os-release): Ubuntu 20.04.6 LTS

[killianmuldoon]

/triage accepted