Feat: Build docker image for the latest three available versions

[clowa]

Solves issue #2

Changes:

• Update versions.json to hold the latest three versions of azure-cli and terraform.
• get-latest-versions workflow now pushes the new version to versions.json and pops the oldest version in the list. The length of the versions list is limited to 3 versions
• docker-buildx workflow now runs a matrix build on the versions in versions.json so each version gets baked with each other.
• Add formatter configuration for json files in vscode to format versions.json consistently across systems