Using `3.8` for the Python devcontainer feature version means it builds from source every time the devcontainer is rebuilt, which is very slow. Using `os-provided` will give us a recent enough version (3.10).
Also install `python-is-python3` so that the bare `python` command points to Python 3 (our scripts seem to expect this).
Add extensions for:
* Bicep
* .NET test runner
* Azure Functions
Include in setup script:
* `cargo-audit` & `cargo-license` (pre-reqs for the CI script)
* Basic devcontainer configuration
* Bump Rust to 1.60, which is required
* Add some more requirements
* Manually install Rust so that cargo-audit can be installed
* Include settings/extensions that were in Rust feature previously
* Install further Rust requirements (from rust-prereqs.sh)
* Install dotnet "by hand"; this should be a bit faster than multiple steps
* Add Python extension to devcontainer
Co-authored-by: Teo Voinea <58236992+tevoinea@users.noreply.github.com>
