feat: add devcontainer

[ReneHezser]

Overview/Summary

With a devcontainer the hugo static website can be built in a local docker container instead of installing the required tooling on the client.

This PR fixes/adds/changes/removes

Closes #1117

Breaking Changes

none

As part of this Pull Request I have

• Read the Contribution Guide and ensured this PR is compliant with the guide
• Checked for duplicate Pull Requests
• Associated it with relevant GitHub Issues or ADO Work Items (Internal Only)
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Ensured PR tests are passing
• Updated relevant and associated documentation (e.g. Contribution Guide, Docs etc.)

[ReneHezser]

Oh my. Wrong branch. I need to clean this up. Give me a minute.
Update: fixed

[ReneHezser]

The linter complains about comments in the devcontainer.json. But they are supported and help understand the file.
Update: I removed the comments

[ross-p-smith]

I'm not sure the comments in the devcontainer.json add any value - it's a well known schema and some of the extensions look like they are just commented out. I agree with the linter! :-) (FWIW!)