[WIP] ec2metadata: Add support for --tags

[samveen]

Metadata tag support was added to the EC2 metadata API in 2022. As per the relevant AWS documentation, both IMDS version 2 and version 1 support exists.

I've used that to implement support for --tags to return a dict, similar to the list returned by --public-keys.

However, before this is merged, I request a quick review to answer whether the output should be

• a python dictonary as is

  {'App': 'cardprocessor', 'Domain': 'stage-cardprocessor.sabpaisa.in', 'Name': 'cardprocessor-asg-member', 'aws:autoscaling:groupName': 'cardprocessor-autoscaling-group', 'aws:ec2launchtemplate:id': 'lt-0c7210c3de4129ea6', 'aws:ec2launchtemplate:version': '4'}
  

• A json dict

  {"App": "cardprocessor", "Domain": "stage-cardprocessor.sabpaisa.in", "Name": "cardprocessor-asg-member", "aws:autoscaling:groupName": "cardprocessor-autoscaling-group", "aws:ec2launchtemplate:id": "lt-0c7210c3de4129ea6", "aws:ec2launchtemplate:version": "4"}
  

• A flat tag: value list like default output of ec2metadata:

  Name: myasg-member
  aws:autoscaling:groupName: myasg
  aws:ec2launchtemplate:id: lt-deadbea1b00b10b155ad
  

• A list as above, but with a tag: prefix:

  tag:Name: myasg-member
  tag:aws:autoscaling:groupName: myasg
  tag:aws:ec2launchtemplate:id: lt-deadbea1b00b10b155ad
  

• Something else better than all the above, which I couldn't figure.

NOTE: I have signed the CLA already