[Feature]: Instance type validation, based on API

[jfbus]

Problem to Solve

New instance types may be added in the future. A CAPOSC upgrade is necessary for validation to pass.

Proposed Solution

Using the ReadVmTypes API call may be used to fetch the list of allowed instance types.

Additional Context

No response

Environment Details

- Kubernetes version (`kubectl version`):
- OS (`/etc/os-release`):
- Kernel (`uname -a`):
- cluster-api-provider-outscale version:
- cluster-api version:
- Install tools:
- Kubernetes distribution:
- Kubernetes distribution version: