Make it easier to get to a correct image_json_path on k8s_kind

Describe the Feature You Want

json paths can be a bit tricky to get right. When calling k8s_kind with an image_json_path to tell Tilt how to find the image for a CRD, Tilt could do more to know when they've got it wrong or right, and to iterate.

Some potential changes:

• When an image_json_path doesn't match an image, search the json for known image names. Give the user a list of image / json_path pairs that appear in the json and ask if they meant one of those.
• Something like https://jsonpathfinder.com/ (whether integrating into Tilt, or providing a hyperlink to a form w/ prepopulated json and path)
• Change missing image_json_path from error to warning, so that users can iterate on an individual CRD instance before being forced to fix all the other CRDs. (which has the con of making it easier for a user to miss when they've got it wrong)

Current Behavior

When an image_json_path doesn't match, you get:

Loading Tiltfile at: /Users/matt/go/src/github.com/tilt-dev/tilt/integration/crd/Tiltfile
Matching (json_path="{.spec.image}"): image is not found

Why Do You Want This?

Iterating on json paths can be annoying in normal cases, and extra annoying when iteration involves a whole Tiltfile:

• Anything else the Tiltfile does means execution itself takes more time.
• Output from the Tiltfile means you have to scan through it to figure out whether you succeeded.

Additional context

related: #5326

Start at the k8s_kind handling for image_json_path and reproduce the current “Matching (json_path=...): image is not found” behavior from the Tiltfile example. Review related issue #5326 and decide which feedback path is in scope; done should include a defined, tested behavior for incorrect or missing paths that makes CRD iteration easier.