dev: add basic devcontainer settings file

Theses settings files are the base needed to declare and
bootstrap development environment on codespaces

Signed-off-by: Emmanuel Roullit <emmanuel.roullit@gmail.com>

.devcontainer/setup.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+curl https://sh.rustup.rs -sSf | sh -s -- -y
+rustup install stable
+bash install.sh