WIP: Create VSCode Dev Container

[SudoBrendan]

• Add a new stage to ci-rp to include all local build tools
• Add config for vscode Dev Containers extension

Which issue this PR addresses:

Improvements for local dev. Makes it so docs/prepare-your-dev-environment.md is basically unused.

What this PR does / why we need it:

Implements VSCode Dev Containers so that local dev environments are in sync with what CI runs (golang versions, other tools and versions, etc)

Test plan for issue:

1. If you don't have it already, install VSCode
2. Set up the Dev Containers Extension

code --install-extension ms-vscode-remote.remote-containers

3. [optional] If you have some "standard" VSCode Extensions you also want in your Dev Containers, you can set those up in File > Preferences > Settings > Extensions > Dev Containers (e.g. I'm a VIM normie, so I added vscodevim.vim / etc)
4. In the bottom left corner of the IDE, a symbol like >< now appears, click it, which opens a dropdown menu - and select Reopen in Dev Container
5. The ci-rp base dev image is built, and then you are launched into the standard dev environment with all required tools installed. You can do things like make generate etc without additional local setup (and all it took was podman and podman-docker!)

Is there any documentation that needs to be updated for this PR?

Yea - will follow up with this before merge (still WIP).

How do you know this will function as expected in production?

N/A - local only

[jaitaiwan]

LGTM so far

[github-actions]

Please rebase pull request.