feat(stats): Add detsys-stats program for getting stats of test run

```
> detsys-stats check --testId [the-testid-to-test] --file [file-describing-properties-to-test]
```

This will output a report for the test, with information how many runs had each
property.

The file should follow the following format:
```
[NAME OF REPORT]

[NAME OF 1 PROPERTY]
[LTL-FORMULA FOR THAT PROPERTY]

[NAME OF 2 PROPERTY]
[LTL-FORMULA FOR THAT PROPERTY]

...

[NAME OF n PROPERTY]
[LTL-FORMULA FOR THAT PROPERTY]
```

default.nix

@@ -24,6 +24,7 @@ let
   ldfi = callPackage ./src/ldfi/default.nix {};
   ltl = callPackage ./src/ltl/default.nix {};
   scheduler = callPackage ./src/scheduler/default.nix {};
+  stats = callPackage ./src/stats/default.nix {};
 in
 
 stdenv.mkDerivation {
@@ -53,7 +54,8 @@ stdenv.mkDerivation {
                           ++ lib.optional (nix-build-all || nix-build-generator) [ generator ]
                           ++ lib.optional (nix-build-all || nix-build-ldfi)      [ ldfi ]
                           ++ lib.optional (nix-build-all || nix-build-ltl)       [ ltl ]
-                          ++ lib.optional (nix-build-all || nix-build-scheduler) [ scheduler ];
+                          ++ lib.optional (nix-build-all || nix-build-scheduler) [ scheduler ]
+                          ++ [ stats ];
 
   installPhase = ''
     mkdir -p $out/bin
@@ -119,6 +121,7 @@ stdenv.mkDerivation {
     install -D $bazelBin/ltl/ltl $out/bin/detsys-ltl
     ''
     }
+    install -D ${stats.out}/bin/detsys-stats $out/bin
     ${if nix-build-scheduler || nix-build-all then ''
     install -D ${scheduler.out}/bin/detsys-scheduler $out/bin
     '' else ''

src/stats/.stylish-haskell.yaml

@@ -0,0 +1,25 @@
+steps:
+  - imports:
+      align: none
+      list_align: with_module_name
+      pad_module_names: false
+      long_list_align: new_line_multiline
+      empty_list_align: inherit
+      list_padding: 7 # length "import "
+      separate_lists: false
+      space_surround: false
+  - language_pragmas:
+      style: vertical
+      align: false
+      remove_redundant: true
+  - simple_align:
+      cases: false
+      top_level_patterns: false
+      records: false
+  - trailing_whitespace: {}
+
+# You need to put any language extensions that's enabled for the entire project
+# here.
+language_extensions: []
+
+columns: 72

src/stats/CHANGELOG.md

@@ -0,0 +1,5 @@
+# Revision history for 
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.

src/stats/LICENSE

@@ -0,0 +1,3 @@
+Copyright (c) 2021 Symbiont Inc.
+
+All rights reserved.

src/stats/README.md

@@ -0,0 +1,3 @@
+### Statistics for a detsys run
+
+> detsys-stats check --testId XXX --file 

src/stats/app/Main.hs

@@ -0,0 +1,56 @@
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE TypeOperators #-}
+
+module Main where
+
+import qualified Description
+import Options.Generic
+import qualified Stats
+
+------------------------------------------------------------------------
+
+-- When building with Bazel we generate a module containing the git commit hash
+-- at compile-time.
+#ifdef __BAZEL_BUILD__
+import GitHash
+-- When building with cabal we expect the git commit hash to be passed in via
+-- CPP flags, i.e. `--ghc-option=-D__GIT_HASH__=\"X\"`.
+#elif defined __GIT_HASH__
+gitHash :: String
+gitHash = __GIT_HASH__
+#else
+gitHash :: String
+gitHash = "unknown"
+#endif
+
+------------------------------------------------------------------------
+
+-- shold we use some other type for FilePath that isn't just alias = [Char]
+data Config
+  = Check
+      { testId :: Int <?> "Which TestId to get stats for",
+        file :: FilePath <?> "File that contains the description of the stats"
+      }
+  | Version
+  deriving (Generic)
+
+instance ParseRecord Config
+
+main :: IO ()
+main = do
+  (cfg, help) <- getWithHelp "Stats"
+  case cfg of
+    Version -> putStrLn gitHash
+    Check {..} -> do
+      input <- readFile $ unHelpful file
+      case Description.parse input of
+        Nothing -> do
+          putStrLn "Can't parse <file>"
+        Just desc -> do
+          (result, nrRuns) <- Stats.gatherInformation (unHelpful testId) desc
+          putStrLn $ Description.pprint nrRuns result

src/stats/cabal.project

@@ -0,0 +1,15 @@
+packages: .
+
+with-compiler: ghc-8.10.4
+
+reject-unconstrained-dependencies: all
+
+constraints: QuickCheck +old-random
+
+package stats
+  ghc-options:
+              -Wall
+              -O2
+
+allow-older: *
+allow-newer: *