Migrate prettier cli options to .prettierrc.json

Author: dyoshikawa

Diff for: .prettierrc.json

@@ -0,0 +1,5 @@
+{
+  "parser": "typescript",
+  "trailingComma": "all",
+  "arrowParens": "avoid"
+}

Diff for: package.json

@@ -14,7 +14,7 @@
   "scripts": {
     "pretest": "npm run format && npm run build",
     "test": "TEST_PORT=1234 TS_NODE_CACHE=0 nyc mocha",
-    "prettier": "prettier --parser typescript --trailing-comma all --arrow-parens avoid \"{lib,test}/**/*.ts\"",
+    "prettier": "prettier \"{lib,test}/**/*.ts\"",
     "format": "npm run prettier -- --write",
     "format:check": "npm run prettier -- -l",
     "clean": "rm -rf dist/*",