[docker-compose] Only rebuild target "service" on container rebuild

For repositories that have multiple containers, it should be possible to limit rebuilds to the single service targeted by devcontainer.json when using docker-compose.

Given a repository like:

monorepo/
  monorepo.code-workspace
  docker-compose.yml
  backend/
    Dockerfile
    .devcontainer/
      devcontainer.json
  frontend/
    Dockerfile
    .devcontainer/ 
      devcontainer.json

Modifications to either devcontainer.json will require triggering a rebuild, but doing so appears to run basically the raw docker-compose build command and then remove/start all containers. (As opposed to docker-compose build backend or docker-compose build frontend.)

In turn, if one VSCode window is open for each of the containers the container not being rebuilt will lose connection to the container since it's been destroyed.

This problem will be more acute if the improved multi-container support in #1460 is implemented but could also be solved separately.