chore: add husky and hook build/format/lint checks to pre-commit

This enforces the same checks locally that will execute in CI

With this, everyone should have a clean / consistent dev environment,
and it will be clear to contributors if they submit code that is not valid
typescript

Additionally, after doing the build it adds the dist/index.js output to the
commit list so contributors can't forget to commit it

.husky/.gitignore

@@ -0,0 +1 @@
+_

.husky/pre-commit

@@ -0,0 +1,3 @@
+#!/bin/sh
+yarn build && git add dist/index.js
+yarn format-check

package.json

@@ -6,7 +6,8 @@
   "scripts": {
     "build": "ncc build src/index.ts --license LICENSES.txt",
     "format": "prettier --write '**/*.ts'",
-    "format-check": "prettier --check '**/*.ts'"
+    "format-check": "prettier --check '**/*.ts'",
+    "prepare": "husky install"
   },
   "dependencies": {
     "@actions/core": "1.2.6",
@@ -15,6 +16,7 @@
   "devDependencies": {
     "@vercel/ncc": "0.27.0",
     "prettier": "2.2.1",
-    "typescript": "4.1.5"
+    "typescript": "4.1.5",
+    "husky": "6.0.0"
   }
 }

yarn.lock

@@ -126,6 +126,11 @@ deprecation@^2.0.0, deprecation@^2.3.1:
   resolved "https://registry.yarnpkg.com/deprecation/-/deprecation-2.3.1.tgz#6368cbdb40abf3373b525ac87e4a260c3a700919"
   integrity sha512-xmHIy4F3scKVwMsQ4WnVaS8bHOx0DmVwRywosKhaILI0ywMDWPtBSku2HNxRvF7jtwDRsoEwYQSfbxj8b7RlJQ==
 
+husky@^6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/husky/-/husky-6.0.0.tgz#810f11869adf51604c32ea577edbc377d7f9319e"
+  integrity sha512-SQS2gDTB7tBN486QSoKPKQItZw97BMOd+Kdb6ghfpBc0yXyzrddI0oDV5MkDAbuB4X2mO3/nj60TRMcYxwzZeQ==
+
 is-plain-object@^4.0.0:
   version "4.1.1"
   resolved "https://registry.yarnpkg.com/is-plain-object/-/is-plain-object-4.1.1.tgz#1a14d6452cbd50790edc7fdaa0aed5a40a35ebb5"