Check upgrade should suggest how to upgrade

[jcchavezs]

Right now getmesh check-upgrade displays:

[Summary of your Istio mesh]
active istioctl version: 1.11.3-tetrate-v0
control plane version: 1.11.3-tetrate-v0

[GetMesh Check]
- There is the available patch for the minor version 1.11-tetrate. We recommend upgrading all 1.11-tetrate versions -> 1.11.6-tetrate-v0

While that is useful we should also provide a hint on how to upgrade, for example brew does:

SOmething like:

Hint: run getmesh switch [the version] would help with autodiscovery and save a couple of commands to figure out how.