feat(devcontainer): add VSCode extensions for ZMK development

ms-vscode.cpptools = C/C++
For editing C/C+ (firmware) and formatting with clang.

plorefice.devicetree = DeviceTree
For editing DeviceTree dts(i) and overlay files.

spadin.zmk-tools = ZMK Tools
For editing ZMK keymaps.

twxs.cmake = CMake
For editing cmake (build) scripts.

trond-snekvik.kconfig-lang = Kconfig for the Zephyr Project
For editing Zephyr Kconfig files.

ms-python.python = Python
For editing Python scripts.

yzhang.markdown-all-in-one = Markdown All in One
For editing markdown files (docs).

dbaeumer.vscode-eslint = ESLint
For linting EMCAScript (JavaScript).

esbenp.prettier-vscode = Prettier - Code formatter
For formatting many web-related languages.

eamodio.gitlens = GitLens
For supercharging git's capabilities.

PR: #475

.devcontainer/devcontainer.json

@@ -7,7 +7,18 @@
     "type=volume,source=zmk-root-user,target=/root",
     "type=volume,source=zmk-config,target=/workspaces/zmk-config"
   ],
-  "extensions": ["ms-vscode.cpptools"],
+  "extensions": [
+    "ms-vscode.cpptools",
+    "plorefice.devicetree",
+    "spadin.zmk-tools",
+    "twxs.cmake",
+    "trond-snekvik.kconfig-lang",
+    "ms-python.python",
+    "yzhang.markdown-all-in-one",
+    "dbaeumer.vscode-eslint",
+    "esbenp.prettier-vscode",
+    "eamodio.gitlens"
+  ],
   "settings": {
     "terminal.integrated.shell.linux": "/bin/bash"
   },