feat: Add buildinfo package to embed version (#840)

This also resolves build time and commit hash using the
Go 1.18 debug/buildinfo package. An external URL is outputted
on running version as well to easily route the caller to a
release or commit.

.vscode/settings.json

@@ -5,6 +5,7 @@
     "coderd",
     "coderdtest",
     "codersdk",
+    "devel",
     "drpc",
     "drpcconn",
     "drpcmux",