Droplet resource additional printer columns

[v-ctiutiu]

Signed-off-by: Cristian Marius Tiutiu v-ctiutiu@digitalocean.com

Description of your changes

This PR adds the ability to print additional columns for droplet resources. It helps visually to have droplet metadata displayed whenever you issue kubectl get droplet commands. On the other hand, it is useful when doing automations (via scripting), because you can fetch droplet information via the CLI.

Examples:

1. Fetch droplet resources with additional details:

   $ kubectl get droplets
   
   NAME          PRIVATE IPV4   PUBLIC IPV4      READY   REGION   SIZE          SYNCED
   nat-gw-nyc1   10.116.0.4     142.93.205.215   True    nyc1     s-1vcpu-1gb   True

2. Extract various fields using kubectl:

• Droplet private IP:

  $ kubectl get droplet nat-gw-nyc1 -o jsonpath="{.status.atProvider.privateIPv4}"
  
  # Outputs - 10.116.0.4

• Droplet public IP:

  $ kubectl get droplet nat-gw-nyc1 -o jsonpath="{.status.atProvider.publicIPv4}"
  
  # Outputs - 142.93.205.215

• Droplet region slug:

  $ kubectl get droplet nat-gw-nyc1 -o jsonpath="{.status.atProvider.region}"
  
  # Outputs - nyc1

• Droplet size slug:

  $ kubectl get droplet nat-gw-nyc1 -o jsonpath="{.status.atProvider.size}"
  
  # Outputs - s-1vcpu-1gb 

I have:

• Read and followed Crossplane's [contribution process].
• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Ran locally using a kind cluster.

[ADustyOldMuffin]

Very cool update!