Adopt changes to Read and Diff

[pgavlin]

1. Return resource inputs as well as resource state from Read()
2. Return a list of properties that changed from Diff()

We implement the former by reading the last applied configuration
from the kubectl.kubernetes.io/last-applied-configuration
annotation in the live object state. If this key is not present, no
inputs are populated and the old inputs are retained. These changes
also update the provider to set this field during Create and
Update.

We implement the latter by scanning the JSON diff and recording the
names of the top-level properties that changed. The engine uses this
information to filter diffs to only those that are semantically
meaningful.

These changes required a couple of bugfixes:

• Old names are only adopted if the old resource was auto-named. This
  ensures that a name must be specified when importing a resource that
  was not autonamed.
• URN to GVK conversion was fixed for resources in the "core" group.
  These resources have no group part in the GVK. Parsing was also
  simplified through the use of pulumi/pulumi's token manipulation
  functions.
• When reading a resource, the GVK for the resource to read is now
  pulled from the URN if it is absent from the inputs.

[pgavlin]

This turns out to have some issues.

Because the set of inputs is pretty broadly overestimated, refreshing the inputs leads to spurious replaces due to apparent changes to auto-populated fields. Here is a simple example: https://asciinema.org/a/e700R9RYcK9pzevwLoXomS4CL

[pgavlin]

I believe that these changes are good to go.

There is a follow-up set of changes that I will make to switch the provider's Diff function over to use openapi.PatchForResourceUpdate to compute diffs. These changes will be necessary for a good import experience in the face of resources that are missing the last-applied-configuration annotation.

[pgavlin]

Ping.

[pgavlin]

I have verified that refreshing resources that were created with prior versions of @pulumi/kubernetes does not cause unexpected diffs despite the lack of the last applied configuration annotation. In these cases, the old inputs are retained as-is and the new behavior remains consistent with the old behavior.

[lblackstone]

Code changes LGTM