Add the cleanupexamples tool

[turkenf]

Description of your changes

We publish some uptest specific codes in the example manifests to the Upbound marketplace. For example, we add the annotation upjet.upbound.io/manual-intervention to skip uptest in resources that require manual intervention, or we add ${Rand.RFC1123Subdomain} to generate a random value in fields that require a unique string.

These uptest specific codes and placeholders can be confusing for users. See as an example: crossplane-contrib/provider-upjet-aws#988

This PR adds the cleanupexamples tool, which removes the above-mentioned confusion.

I have:

• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

For now, this tool has been tested manually in my local environment. We will do more testing when we integrate the code into the build process.

• Below is an example input YAML:

apiVersion: apigateway.aws.upbound.io/v1beta1
kind: BasePathMapping
metadata:
  annotations:
    crossplane.io/external-name: test name
    upjet.upbound.io/manual-intervention: "The BasePathMapping resource needs a DomainName and DomainName resource needs valid certificates."
    uptest.upbound.io/timeout: "3600" # one hour timeout
    uptest.upbound.io/disable-import: "true"
    uptest.upbound.io/pre-delete-hook: testhooks/delete
  labels:
    testing.upbound.io/example-name: domainname
  name: example-${Rand.RFC1123Subdomain}
spec:
  forProvider:
    apiId: demo
    domain: example
    region: us-west-1

• and the output YAML generated with the tool:

apiVersion: apigateway.aws.upbound.io/v1beta1
kind: BasePathMapping
metadata:
  annotations:
    crossplane.io/external-name: test name
  labels:
    testing.upbound.io/example-name: domainname
  name: example-random
spec:
  forProvider:
    apiId: demo
    domain: example
    region: us-west-1

[mergenci]

Thanks @turkenf, especially for providing unit tests as well 😎 Please find my comments below. I'm approving the PR, in case you would like to merge soon. I would be happy to see another review though, just to have another point of view.

[sergenyalcin]

Thanks @turkenf for your great work here. LGTM!