[flow-dev-tools] Changelog generation improvements

Summary:
I've added logic to automatically categorize and format the changelog based on the category specific in the diff summary.

I've also updated the diff signals butterfly rule to enforce these categories as well: https://fburl.com/butterfly/cw1xu6d1

Reviewed By: SamChou19815

Differential Revision: D66797754

fbshipit-source-id: 4929e654d8ed210cbee5ee8f20529eb16dd83144

packages/flow-dev-tools/package.json

@@ -20,7 +20,8 @@
     "flow-dev-tools": "./bin/tool"
   },
   "scripts": {
-    "test": "node src/__tests__/all-tests.js"
+    "test": "node src/__tests__/all-tests.js",
+    "facebook-tests": "node src/facebook/__tests__/all-facebook-tests.js"
   },
   "engines": {
     "node": ">=12"