feat: ensure related go source and vscode plugins are installed in devcontainer

.devcontainer/devcontainer.json

@@ -7,12 +7,19 @@
     "DOKKU_HOST_ROOT": "${localWorkspaceFolder}/tmp/data/home/dokku",
     "GO_ROOT_MOUNT": "${localWorkspaceFolder}:/go/src/github.com/dokku/dokku"
   },
+  "extensions": [
+    "golang.go",
+    "mads-hartmann.bash-ide-vscode",
+    "ms-vscode.makefile-tools"
+  ],
   "initializeCommand": ["mkdir", "-p", "tmp/data"],
   "mounts": [
     "source=/var/run/docker.sock,target=/var/run/docker.sock,type=bind",
     "source=${localWorkspaceFolder}/tmp/data/,target=/mnt/dokku/,type=bind"
   ],
   "overrideCommand": false,
-  "postCreateCommand": ["make", "setup-deploy-tests"],
-  "runArgs": ["--init"]
+  "postCreateCommand": "make setup-deploy-tests && go-mod-downloadall",
+  "runArgs": ["--init"],
+  "workspaceFolder": "/root/go/src/github.com/dokku/dokku",
+  "workspaceMount": "type=bind,source=${localWorkspaceFolder},target=/root/go/src/github.com/dokku/dokku,consistency=cached"
 }