Add support to delete ec2 key pairs using cloud-nuke

[hongil0316]

Description

Fixes https://gruntwork.atlassian.net/browse/CORE-284.

Testing

• Tested running the cloud-nuke command line locally to delete an existing EC2 key pair

aws-vault exec gruntwork-customer-access-test -- go run main.go aws --resource-type ec2-keypairs

• Unit tests that creates & nuke an EC2 key pair.
• Tested aws-inspect on ec2 key pair

aws-vault exec gruntwork-customer-access-test -- go run main.go inspect-aws --resource-type ec2-keypairs

TODOs

Read the Gruntwork contribution guidelines.

• Update the docs.
• Run the relevant tests successfully, including pre-commit checks.
• Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.
• Include release notes. If this PR is backward incompatible, include a migration guide.
• Attention Grunts - if this PR adds support for a new resource, ensure the nuke_sandbox and nuke_phxdevops jobs in .circleci/config.yml have been updated with appropriate exclusions (either directly in the job or via the .circleci/nuke_config.yml file) to prevent nuking IAM roles, groups, resources, etc that are important for the test accounts.

Release Notes (draft)

Added / Removed / Updated [X].

Migration Guide

[ellisonc]

There's a folder in the repo called config that handles resources when using a config.yml file. The new resource should be added to the Config struct as well as any usages.

Readme also needs to be updated

[ellisonc]

This function should contain logic for deciding if an ec2 key pair should be included in the list to be nuked. If you do a repo search for shouldInclude* you should find examples. This is what powers the regex and time based filtering

[hongil0316]

Ah that's nice. I wonder if that should be a separate ticket to handle? https://gruntwork.atlassian.net/browse/CORE-284 -- the acceptance criteria does not seem to mention about the capability to support such feature.

[ellisonc]

I don't have a problem with adding it to a separate ticket, but I don't think we should release it without this functionality since all of the other resources support it. Especially with a tool designed for destruction like cloud-nuke. It would be very easy for someone to create a config file with a regex and accidentally delete something because the regex feature wasn't added.

[hongil0316]

Ah that's a great point. Let's add that as part of this if that's the case. Let me update the PR 👍

[hongil0316]

There's a folder in the repo called config that handles resources when using a config.yml file. The new resource should be added to the Config struct as well as any usages.

Readme also needs to be updated

Got it. Updated.

[ellisonc]

Need to update the readme and add release notes to the PR

[hongil0316]

Need to update the readme and add release notes to the PR

Hmm I though I updated the readme :S I guess it was not included somehow.
Don't we auto-generate the release note based on the PRs?

Is this one special because it's an open source repository?