Install SSH server into devcontainer image (mastodon#22679)

Author: kyori19

.devcontainer/devcontainer.json

@@ -15,6 +15,12 @@
     "webben.browserslist"
   ],
 
+  "features": {
+    "ghcr.io/devcontainers/features/sshd:1": {
+      "version": "latest"
+    }
+  },
+
   // Use 'forwardPorts' to make a list of ports inside the container available locally.
   // This can be used to network with other containers or the host.
   "forwardPorts": [3000, 4000],