Implement fallback install and outputs (#2)

* Add better version support. Restructure code. Implement OS agnostic fallback

* Support latest for cabal and stack. Add enable-stack option.

* Add outputs

* Update documentation. Change default for GHC to latest.

package.json

@@ -5,15 +5,7 @@
   "description": "setup haskell action",
   "main": "src/setup-haskell.ts",
   "scripts": {
-    "check:type": "tsc --noEmit",
-    "check:format": "prettier --check **/*.{ts,json}",
-    "check:lint": "eslint src/**/*.ts",
-    "test": "jest",
-    "format": "prettier --write **/*.{ts,json}",
-    "pack": "ncc build",
-    "_git-add": "git add dist",
-    "pre-push": "run-p check:* test",
-    "pre-commit": "npm-run-all format pack _git-add"
+    "test": "jest"
   },
   "repository": {
     "type": "git",
@@ -30,31 +22,34 @@
   "license": "MIT",
   "dependencies": {
     "@actions/core": "^1.2.3",
+    "@actions/exec": "^1.0.3",
+    "@actions/glob": "^0.1.0",
     "@actions/io": "^1.0.2",
     "@actions/tool-cache": "^1.3.3",
     "js-yaml": "^3.13.1"
   },
   "devDependencies": {
-    "@types/jest": "^25.1.4",
-    "@types/js-yaml": "^3.12.2",
-    "@types/node": "^13.9.1",
-    "@typescript-eslint/parser": "^2.24.0",
-    "@zeit/ncc": "^0.21.1",
+    "@types/jest": "^25.2.1",
+    "@types/js-yaml": "^3.12.3",
+    "@types/node": "^13.13.2",
+    "@typescript-eslint/parser": "^2.29.0",
+    "@typescript-eslint/eslint-plugin": "^2.29.0",
+    "@zeit/ncc": "^0.22.1",
     "eslint": "^6.8.0",
     "eslint-plugin-github": "^3.4.1",
     "eslint-plugin-jest": "^23.8.2",
-    "husky": "^4.2.3",
-    "jest": "^25.1.0",
-    "jest-circus": "^25.1.0",
-    "npm-run-all": "^4.1.5",
-    "prettier": "^1.19.1",
-    "ts-jest": "^25.2.1",
+    "husky": "^4.2.5",
+    "jest": "^25.4.0",
+    "jest-circus": "^25.4.0",
+    "lint-staged": "^10.1.7",
+    "prettier": "^2.0.5",
+    "ts-jest": "^25.4.0",
     "typescript": "^3.8.3"
   },
   "husky": {
     "hooks": {
-      "pre-commit": "npm run pre-commit",
-      "pre-push": "npm run pre-push"
+      "pre-commit": "lint-staged",
+      "pre-push": "npm test"
     }
   }
 }