Support Ambient Mode

[hercynium]

Right now, Fortsa completely ignores ambient mode. However, there's some things we can do to support it. For example, we can look for changes to the namespace label istio.io/dataplane-mode. If Ambient is enabled on a namespace, we should restart the workloads so they no longer have sidecars. Conversely, if ambient mode is removed from a namespace, we should do the same thing - so sidecars are added.

For more info on the logic we need to support, see the following:

• https://istio.io/latest/docs/ambient/usage/add-workloads/#pod-selection-logic-for-ambient-and-sidecar-modes
• https://istio.io/latest/docs/reference/config/labels/#IoIstioDataplaneMode
• https://istio.io/latest/docs/reference/config/annotations/#AmbientRedirection

Note that this is currently considered a "nice to have" feature, and not necessarily a requirement unless the users ask for it.

If you want this feature, please let me know in the comments!

[hercynium]

Labels to look at:

• istio.io/dataplane-mode
• istio.io/rev
• istio.io/tag
• sidecar.istio.io/inject

Annotations to look at:

• ambient.istio.io/redirection
• istio.io/rev
• sidecar.istio.io/inject