[fs-detectors] Use json5 parser for Rush to have valid json parsing (#8645)

### Related Issues

Parse `rush.json` files with `json5` because it is very common for these
to have comments in them

[Template for people to clone for
Rush](https://rushjs.io/pages/configs/rush_json/) which has comments in
it as a default which most people will clone
 
Docs of Rush showing to not use `JSON.parse`

https://rushjs.io/pages/help/faq/#why-do-rushs-json-config-files-contain--comments-that-github-shows-in-red

Added in tests with block comments and single line comments

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#### Tests

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Co-authored-by: Sean Massa <EndangeredMassa@gmail.com>

packages/fs-detectors/test/fixtures/40-rush-monorepo/rush.json

@@ -2,7 +2,6 @@
   "$schema": "https://developer.microsoft.com/json-schemas/rush/v5/rush.schema.json",
 
   "rushVersion": "5.76.1",
-
   "pnpmVersion": "6.7.1",
 
   "pnpmOptions": {
@@ -22,6 +21,7 @@
 
     "postRushBuild": []
   },
+  // comment
   "variants": [],
   "projects": [
     {

packages/fs-detectors/test/fixtures/42-rush-json-invalid/rush.json

@@ -12,7 +12,9 @@
   "nodeSupportedVersionRange": ">=12.13.0 <13.0.0 || >=14.15.0 <15.0.0 || >=16.13.0 <17.0.0",
 
   "gitPolicy": {},
-
+  /* 
+  this is a comment
+  */
   "repository": {},
   "eventHooks": {
     "preRushInstall": [],