Add ttr, the time-to-readiness reporting tool for managed resources

[ulucinar]

Description of your changes

Fixes #69

This PR proposes a standalone, reusable time-to-readiness (ttr) reporting tool for managed resources. ttr is defined as the time it takes for a managed resource to acquire the Ready=True condition from the moment it's provisioned (metadata.creationTimestamp), measured in seconds and was proposed here. This tool can be run against a cluster to collect the ttr measurements of a subset of managed resources found in the cluster. The subset of managed resources can be specified with a list of filter strings via the --filters command-line option.

Some example invocations of the tool are:

• ttr -> Report on all managed resources
• ttr -f cognitoidp.aws.upbound.io/v1beta1/UserPool/example
• ttr -f //UserPool/ -> Report all UserPool resources
• ttr -f //UserPool/ -f //VPC/ -> Report all UserPool and VPC resources
• ttr -f cognitoidp.aws.upbound.io/// -> Report all resources in the group
• ttr -f ///example-.* -> Report all resources with names prefixed by example-

Sample output:

❯ ttr
cognitoidp.aws.upbound.io/v1beta1/UserPool/example-alper:20
cognitoidp.aws.upbound.io/v1beta1/UserPool/example-alper2:18

The output syntax is <API group>/<API version>/<Kind>/<metadata.name>:<ttr> on each line. The reported ttr is in seconds.

Command's usage document:

❯ ./_output/bin/darwin_arm64/ttr -h
Reports the time-to-readiness measurements for a subset of the managed resources in a Kubernetes cluster

Usage:
  ttr [flags]

Examples:
ttr --kubeconfig=./kubeconfig

Flags:
      --as string                      Username to impersonate for the operation. User could be a regular user or a service account in a namespace.
      --as-group stringArray           Group to impersonate for the operation, this flag can be repeated to specify multiple groups.
      --as-uid string                  UID to impersonate for the operation.
      --cache-dir string               Default cache directory (default "/Users/alper/.kube/cache")
      --certificate-authority string   Path to a cert file for the certificate authority
      --client-certificate string      Path to a client certificate file for TLS
      --client-key string              Path to a client key file for TLS
      --cluster string                 The name of the kubeconfig cluster to use
      --context string                 The name of the kubeconfig context to use
      --disable-compression            If true, opt-out of response compression for all requests to the server
  -f, --filters stringArray            Zero or more filter expressions each with the following syntax: [group]/[version]/[kind]/[name regex]. Can be repeated. Filters managed resources with the specified APIs and names. Missing entries should be specified as empty strings.
  -h, --help                           help for ttr
      --insecure-skip-tls-verify       If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure
      --kubeconfig string              Path to the kubeconfig file to use for CLI requests.
  -n, --namespace string               If present, the namespace scope for this CLI request
      --request-timeout string         The length of time to wait before giving up on a single server request. Non-zero values should contain a corresponding time unit (e.g. 1s, 2m, 3h). A value of zero means don't timeout requests. (default "0")
  -s, --server string                  The address and port of the Kubernetes API server
      --tls-server-name string         Server name to use for server certificate validation. If it is not provided, the hostname used to contact the server is used
      --token string                   Bearer token for authentication to the API server
      --user string                    The name of the kubeconfig user to use

I have:

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

How has this code been tested

Tested against provider-aws resources.

[sergenyalcin]

Thanks @ulucinar LGTM!