Modernize devcontainer configuration

Updates:
- Ubuntu 22.04 LTS (jammy) instead of 20.04 (focal)
- Modern devcontainers base image
- Install all cross-compilation toolchains:
  * gcc-multilib/g++-multilib (x86 32-bit)
  * gcc-arm-linux-gnueabi (ARM32)
  * gcc-aarch64-linux-gnu (ARM64)
  * gcc-riscv64-linux-gnu (RISC-V)
- Install qemu-user for emulation testing
- Install Python 3 for build scripts
- Updated settings format (customizations instead of deprecated settings)
- Fixed deprecated terminal.integrated.shell.linux setting
- Added postCreateCommand to verify environment
- Improved container name and comments

Author: kristjanvalur

.devcontainer/Dockerfile

@@ -1,11 +1,24 @@
-# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.166.1/containers/ubuntu/.devcontainer/base.Dockerfile
+# stackman development container
+# Includes cross-compilation toolchains for all supported platforms
 
-# [Choice] Ubuntu version: bionic, focal
-ARG VARIANT="focal"
-FROM mcr.microsoft.com/vscode/devcontainers/base:0-${VARIANT}
+ARG VARIANT="jammy"
+FROM mcr.microsoft.com/devcontainers/base:ubuntu-${VARIANT}
 
-# [Optional] Uncomment this section to install additional OS packages.
+# Install build tools and cross-compilation toolchains
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-    && apt-get -y install --no-install-recommends build-essential
-
-
+    && apt-get -y install --no-install-recommends \
+        build-essential \
+        gcc-multilib \
+        g++-multilib \
+        gcc-arm-linux-gnueabi \
+        g++-arm-linux-gnueabi \
+        gcc-aarch64-linux-gnu \
+        g++-aarch64-linux-gnu \
+        gcc-riscv64-linux-gnu \
+        g++-riscv64-linux-gnu \
+        qemu-user \
+        python3 \
+        python3-pip \
+    && apt-get autoremove -y \
+    && apt-get clean -y \
+    && rm -rf /var/lib/apt/lists/*

.devcontainer/devcontainer.json

@@ -1,29 +1,32 @@
-// For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
-// https://github.com/microsoft/vscode-dev-containers/tree/v0.166.1/containers/ubuntu
+// For format details, see https://aka.ms/devcontainer.json
 {
-	"name": "Ubuntu",
+	"name": "stackman Development",
 	"build": {
 		"dockerfile": "Dockerfile",
-		// Update 'VARIANT' to pick an Ubuntu version: focal, bionic
-		"args": { "VARIANT": "focal" }
+		"args": { 
+			"VARIANT": "jammy"  // Ubuntu 22.04 LTS
+		}
 	},
 
 	// Set *default* container specific settings.json values on container create.
-	"settings": { 
-		"terminal.integrated.shell.linux": "/bin/bash"
+	"customizations": {
+		"vscode": {
+			"settings": {
+				"terminal.integrated.defaultProfile.linux": "bash"
+			},
+			"extensions": [
+				"ms-vscode.cpptools",
+				"ms-vscode.cpptools-extension-pack"
+			]
+		}
 	},
 
-	// Add the IDs of extensions you want installed when the container is created.
-	"extensions": [
-		"ms-vscode.cpptools"
-	],
-
 	// Use 'forwardPorts' to make a list of ports inside the container available locally.
 	// "forwardPorts": [],
 
 	// Use 'postCreateCommand' to run commands after the container is created.
-	// "postCreateCommand": "uname -a",
+	"postCreateCommand": "make --version && gcc --version && make abiname",
 
-	// Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
 	"remoteUser": "vscode"
 }