Detect self-hosted runners not matching a GitHub-hosted runner image

* And give instructions for that case.
* Get the OS and OS version ourselves since some users set ImageOS incorrectly.
* This partially reverts commit ad1ebae995.

package.json

@@ -27,6 +27,8 @@
     "@actions/exec": "^1.1.1",
     "@actions/io": "^1.1.2",
     "@actions/tool-cache": "^2",
+    "linux-os-info": "^2.0.0",
+    "macos-release": "^3.1.0",
     "semver": "^7.3.7"
   },
   "devDependencies": {