Add AZD feature

[pamelafox]

Purpose

There's now an azd feature for dev containers, which will automatically download the appropriate azd for your architecture (arm/amd) so platform emulation is no longer needed. This PR updates the dev container to use that feature and also removes some other unnecessary bits.

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[X] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• Open in Codespaces
• Confirm azd command works
• Confirm "play and debug" works

[pamelafox]

@shreyabatra4 Please review, thanks.