balloons: add "preserve" option to match containers whose pinning must not be modified

[askervin]

Some containers must be able to run with their resources unmanaged by a resource policy. Currently this can be achieved only by annotating pods. However, in certain environments it is more convenient to change a node-specific policy configuration rather than change annotations of workloads.

This PR adds such an option to the balloons policy. Once the option takes its final shape, we can add similar option to the topology-aware policy, too.

[klihub]

LGTM, but I wouldn't call this ignored but preserved, since it basically has the same effect as annotating a container preserved.

[askervin]

Renamed to preserve. Now it's aligned with the preserve annotation.

Thanks for spotting the typos! I'd prefer fixing typos in resmgr.Expression documentation (in pkg/apis/resmgr/v1alpha1/types.go) in a separate PR. That's because including those fixes into this patch series would only make it more difficult to understand, just by checking modified files in the PR, that which exact source files needed a change in order to add a new option+implementation+test+documentation. Sort of minimizing the blast radius. What do you think, @fmuyassarov?

Because the fix modifies generated code files in this and another option, filing that PR would cause conflicts before this PR is merged. So I could file it after merging.

[fmuyassarov]

Thanks for spotting the typos! I'd prefer fixing typos in resmgr.Expression documentation (in pkg/apis/resmgr/v1alpha1/types.go) in a separate PR. That's because including those fixes into this patch series would only make it more difficult to understand, just by checking modified files in the PR, that which exact source files needed a change in order to add a new option+implementation+test+documentation. Sort of minimizing the blast radius. What do you think, @fmuyassarov?

Yes, sure. As you prefer.

[klihub]

Renamed to preserve. Now it's aligned with the preserve annotation.

Thanks for spotting the typos! I'd prefer fixing typos in resmgr.Expression documentation (in pkg/apis/resmgr/v1alpha1/types.go) in a separate PR. That's because including those fixes into this patch series would only make it more difficult to understand, just by checking modified files in the PR, that which exact source files needed a change in order to add a new option+implementation+test+documentation. Sort of minimizing the blast radius. What do you think, @fmuyassarov?

Because the fix modifies generated code files in this and another option, filing that PR would cause conflicts before this PR is merged. So I could file it after merging.

And I hope we could get #356 merged soon (once libmem is in) and that will bring in a bunch of spelling fixes and make it easier to avoid them in the future.

[fmuyassarov]

LGTM