Idea: Image autocomplete suggestions

[v-mengwe]

OS: All
Build Version: 20210204.1

Repro Steps:

1. Create a project and open in VS Code -> Open the docker-compose.yml file.
2. Type the following into the docker-compose.yml file:

     version: '2'
     redis:
         image: 

3. Press CTRL+SPACE -> Select "centos" -> Press CTRL+SPACE -> Select an image.
4. Cursor is placed after "centos" -> Press CTRL+SPACE -> Select an image(same/different).
5. Check whether the image is replaced automatically.

Actual:
The image is not replaced automatically.

Suggestion:
It would be better to replace the image automatically.

[bwateratmsft]

Good suggestion! We're working on our Compose intellisense story as a whole, so I added this idea to our checklist on microsoft/vscode-docker#2539.