QSP-6: Enforces crypto-secure PRNGs (#6401)

* adds cryptorand analyzer

* better naming

* rely on suffix

* sync/pending_* use crypto/rand

* define shared/rand

* updates fetcher

* fixes rand issue in sync package

* gofmt

* shared/rand: more docs + add exclusion nogo_config.json

* updates validator/assignments

* updates comment

* fixes remaning cases

* re-arranges comments

* fixes tests

* renames in shared/rand API

* adds simple no-panic test

* gazelle

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

nogo_config.json

@@ -34,7 +34,7 @@
     "exclude_files": {
       "external/.*": "Third party code"
     }
-  }, 
+  },
   "copylocks": {
     "exclude_files": {
       "external/.*": "Third party code"
@@ -44,7 +44,7 @@
     "exclude_files": {
       "external/.*": "Third party code"
     }
-  }, 
+  },
   "cgocall": {
     "exclude_files": {
       "external/.*": "Third party code"
@@ -70,8 +70,8 @@
   },
   "roughtime": {
     "only_files": {
-      "beacon-chain/.*":  "",
-      "shared/.*":  "",
+      "beacon-chain/.*": "",
+      "shared/.*": "",
       "validator/.*": ""
     },
     "exclude_files": {
@@ -96,7 +96,19 @@
   },
   "featureconfig": {
     "only_files": {
-      ".*_test\\.go":  "Only tests"
+      ".*_test\\.go": "Only tests"
+    }
+  },
+  "cryptorand": {
+    "only_files": {
+      "beacon-chain/.*": "",
+      "shared/.*": "",
+      "validator/.*": ""
+    },
+    "exclude_files": {
+      ".*/.*_test\\.go": "Tests are OK to use weak crypto",
+      "shared/rand/rand\\.go": "Abstracts CSPRNGs for common use",
+      "shared/aggregation/testing/bitlistutils.go": "Test-only package"
     }
   }
 }