remove dev container support again

.devcontainer/Dockerfile

@@ -1,16 +0,0 @@
-FROM ubuntu:18.04
-
-RUN apt-get update
-RUN apt-get install -y \
-  curl \
-  git \
-  gnupg2 \
-  jq \
-  sudo \
-  zsh \
-  vim \
-  build-essential \
-  openssl
-RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
-
-ENV PATH="/root/.cargo/bin:$PATH"

.devcontainer/devcontainer.json

@@ -1,20 +0,0 @@
-{
-	"name": "Rust",
-	"build": {
-		"dockerfile": "Dockerfile"
-	},
-	// Set *default* container specific settings.json values on container create.
-	"settings": {
-		"terminal.integrated.shell.linux": "/bin/bash",
-		// VS Code don't watch files under ./target
-		"files.watcherExclude": {
-			"**/target/**": true
-		}
-	},
-	// Add the IDs of extensions you want installed when the container is created.
-	"extensions": [
-		"matklad.rust-analyzer",
-		"bungcip.better-toml",
-		"serayuzgur.crates",
-	]
-}