Include children when targeting resources with children.

[komalali]

Description

Prior to this change, when a component was targeted without including all of its children in the list of targets, it would result in an error like below:

Diagnostics:
  infrastructure:k8s-istio-operator (web-dev):
    error: Cannot delete parent resource 'urn:pulumi:istio-operator::infrastructure::infrastructure:k8s-istio-operator::web-dev' without also deleting child 'urn:pulumi:istio-operator::infrastructure::infrastructure:k8s-istio-operator$kubernetes:yaml:ConfigGroup::web-dev'

However, when a component is targeted, it is logical that the user intended to also target the component's children, since the component itself is a wrapper for all of its children. This PR changes the behavior to include children when a component is targeted instead of erroring.

Note: This changes the default behavior of --target to include a component's children. Should this be behind a flag (should we be including this in --target-dependents)? Do we want some way to preserve the old behavior?

Fixes #4032

Checklist

• I have added tests that prove my fix is effective or that my feature works

• I have updated the CHANGELOG-PENDING file with my change

• Yes, there are changes in this PR that warrants bumping the Pulumi Service API version

[komalali]

@pgavlin I know we discussed solving this at the CLI level - is there any drawback to fixing it here?

[komalali]

Tagged @lukehoban and @infin8x to consider the change from default behavior and how we want to handle that.

[pgavlin]

Excellent tests!

One nit + one suggestion re: finding the transitive children of a resource.