feat: add ESM builds for packages used in browser (#459)

* feat: add ESM builds for packages used in browser

* fix(id-generator-aws-xray): missed including esm files

Author: t2t2

package.json

@@ -3,19 +3,20 @@
   "version": "0.16.0",
   "description": "OpenTelemetry AWS Xray propagator provides context propagation for systems that are using AWS X-Ray format.",
   "main": "build/src/index.js",
+  "module": "build/esm/index.js",
   "types": "build/src/index.d.ts",
   "repository": "open-telemetry/opentelemetry-js-contrib",
   "scripts": {
     "precompile": "tsc --version",
-    "compile": "tsc --build",
-    "clean": "tsc --build --clean",
+    "compile": "tsc --build tsconfig.json tsconfig.esm.json",
+    "clean": "tsc --build --clean tsconfig.json tsconfig.esm.json",
     "test": "nyc ts-mocha -p tsconfig.json test/**/*.test.ts",
     "test:browser": "nyc karma start --single-run",
     "codecov": "nyc report --reporter=json && codecov -f coverage/*.json -p ../../",
     "lint": "eslint . --ext .ts",
     "lint:fix": "eslint . --ext .ts --fix",
     "version": "node ../../scripts/version-update.js",
-    "watch": "tsc --build --watch",
+    "watch": "tsc --build --watch tsconfig.json tsconfig.esm.json",
     "prepare": "npm run compile"
   },
   "keywords": [
@@ -31,6 +32,9 @@
     "node": ">=8.0.0"
   },
   "files": [
+    "build/esm/**/*.js",
+    "build/esm/**/*.js.map",
+    "build/esm/**/*.d.ts",
     "build/src/**/*.js",
     "build/src/**/*.js.map",
     "build/src/**/*.d.ts",

tsconfig.esm.json

@@ -0,0 +1,11 @@
+{
+  "extends": "../../tsconfig.base.esm.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "build/esm",
+    "tsBuildInfoFile": "build/esm/tsconfig.esm.tsbuildinfo"
+  },
+  "include": [
+    "src/**/*.ts"
+  ]
+}