Show redefined attribute's original value as an inlay hint when extending services in Compose

[rcjsuen]

Given this YAML file, we should use an inlay hint to show the original value of hostname from test since test2 has chosen to override this value. We will only consider service extensions in the current file for starters.

services:
  test:
    image: redis:alpine
    hostname: hello
  test2:
    extends: test
    hostname: world