build: add a format script based on prettier

[paulfouquet]

Motivation

Before pushing some changes, I want my modifications to have a correct format based on the LINZ prettier config.

Modification

Add a format script that can be run manually using npm run format

Checklist

• Tests updated N/A
• Docs updated N/A
• Issue linked in Title N/A

[paulfouquet]

There are a couple of issues with prettier 🤔

• not adding the newline at the end of the files
• in github actions workflows, ${{env.MY_VAR}} should be formatted to ${{ env.MY_VAR }}, but it's not