feat(esmodule): output esmodule along with commonjs

BREAKING CHANGE: specifies "module" field in package.json

package.json

@@ -13,19 +13,20 @@
 	"license": "MIT",
 	"author": "Keiichiro Amemiya <hoishinxii@gmail.com>",
 	"files": [
-		"out",
+		"cjs",
+		"esm",
 		"src",
 		"!src/__tests__"
 	],
-	"main": "out/index.js",
-	"types": "out/index.d.ts",
+	"main": "cjs/index.js",
+	"module": "esm/index.js",
+	"types": "cjs/index.d.ts",
 	"scripts": {
 		"alpha": "npm version prerelease --preid=alpha",
 		"beta": "npm version prerelease --preid=beta",
 		"prebuild": "del out",
-		"build": "tsc",
-		"prepublishOnly": "yarn && yarn build",
-		"pretest": "yarn build",
+		"build": "tsc -p tsconfig.cjs.json && tsc -p tsconfig.esm.json",
+		"prepublishOnly": "yarn build",
 		"test": "jest",
 		"version": "conventional-changelog -p angular -i CHANGELOG.md -s -r 0 && git add CHANGELOG.md"
 	},

tsconfig.cjs.json

@@ -0,0 +1,13 @@
+{
+	"extends": "./tsconfig",
+	"compilerOptions": {
+		"module": "commonjs",
+		"outDir": "cjs"
+	},
+	"include": [
+		"src/**/*.ts",
+		"src/**/*.tsx",
+		"node_modules/nodecg/types/browser.d.ts"
+	],
+	"exclude": ["**/__tests__"]
+}

tsconfig.esm.json

@@ -0,0 +1,13 @@
+{
+	"extends": "./tsconfig",
+	"compilerOptions": {
+		"module": "es2015",
+		"outDir": "esm"
+	},
+	"include": [
+		"src/**/*.ts",
+		"src/**/*.tsx",
+		"node_modules/nodecg/types/browser.d.ts"
+	],
+	"exclude": ["**/__tests__"]
+}

tsconfig.json

@@ -2,14 +2,11 @@
 	"extends": "@hoishin/tsconfig",
 	"compilerOptions": {
 		"target": "es2018",
-		"module": "commonjs",
 		"lib": ["es2018", "dom"],
 		"jsx": "react",
 		"declaration": true,
 		"declarationMap": true,
 		"sourceMap": true,
-		"outDir": "out",
-
 		"moduleResolution": "node"
 	},
 	"include": [