[WIP]: Add listener based on the machine label and listener label

[Shilpa-Gokul]

What this PR does / why we need it:
This PR is not ready to review yet.
Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1678

Special notes for your reviewer:

/area provider/ibmcloud

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

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[mkumatag]

• This needs to be optional and also omitempty
• Is there a scope for multiple selector? @Karthik-K-N
• what will happen if someone changes this field? are we allowing this field to be changed? if not - can we block it?

[Karthik-K-N]

what will happen if someone changes this field?

I think to start with we can make this field immutable? so we can block the changes to the field.

Is there a scope for multiple selector?

You mean like configure the listener to multiple machine like Port 22 for machine-1 and machine-2

There are two options

1. Add 2 listener with same port but with different selector
2. Allow label to have multiple machine separated by comma(,) and add support for this in controller
   like
   infrastructure.cluster.x-k8s.io/machine-name: machine1, machine2

[mkumatag]

my bad, this make sense.. may be its worth adding more examples so that it becomes clear for the consumers.
I find this reference useful - https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/

[mkumatag]

@Shilpa-Gokul its worth writing a design doc with more examples, lets do that before this PR.

I like the way it is written here - #2139 for one of the work.

[Karthik-K-N]

@Shilpa-Gokul its worth writing a design doc with more examples, lets do that before this PR.

I like the way it is written here - #2139 for one of the work.

Yes, We have already planned to do so, With some diagrams and examples, That would become easier for review and to see if there is any better approach as well, This is also one of the reasons for keeping this as WIP and also adding UT with only happy paths.