Update buildchain to use rollup in order to improve esm support

The library exported an esm version, however it didn't work
with all esm tools becase some require "type": "module" to be
set, or the files to end in ".mjs". By moving over to rollup,
we can output the esm files with the ".mjs" extension which
makes this library work with vite.

This change is based on the approach which Chat decided on:
yext/chat-ui-react#38

J=BACK-2527
TEST=manual

Manually ran the test site locally and confirmed the requests
still fire correctly. I still need to test this with vite.

package.json

@@ -3,7 +3,7 @@
   "version": "2.4.0",
   "description": "Typescript Networking Library for the Yext Search API",
   "main": "./dist/commonjs/src/index.js",
-  "module": "./dist/esm/src/index.js",
+  "module": "./dist/esm/src/index.mjs",
   "types": "./dist/bundle.d.ts",
   "sideEffects": false,
   "keywords": [
@@ -30,13 +30,11 @@
   "scripts": {
     "test": "npm run lint && jest",
     "lint": "eslint . --max-warnings=0",
-    "tsc-cjs": "tsc -p tsconfig.cjs.json",
-    "tsc-esm": "tsc -p tsconfig.esm.json",
-    "tsc": "npm run tsc-cjs && npm run tsc-esm",
     "build-legacy-bundle": "npx webpack",
-    "build": "rm -rf dist/** && npm run tsc && npm run build-legacy-bundle && npm run api-extractor && npm run generate-docs",
-    "build-ci": "npm run tsc-cjs && npm run api-extractor && npm run generate-docs",
-    "dev": "npm run tsc-esm -- --watch",
+    "build:js": "rollup --config rollup.config.mjs",
+    "build": "rm -rf dist/** && npm run build:js && npm run build-legacy-bundle && npm run api-extractor && npm run generate-docs",
+    "build-ci": "npm run build:js && npm run api-extractor && npm run generate-docs",
+    "dev": "npm run build:js -- --watch",
     "prepublishOnly": "npm run build",
     "api-extractor": "api-extractor run --local --verbose",
     "generate-docs": "api-documenter markdown --input-folder temp --output-folder docs && rm -rf temp && npm run generate-notices",
@@ -59,6 +57,7 @@
     "@babel/preset-typescript": "^7.12.1",
     "@microsoft/api-documenter": "^7.13.76",
     "@microsoft/api-extractor": "^7.19.2",
+    "@rollup/plugin-json": "^6.0.0",
     "@types/jest": "^28.1.1",
     "@typescript-eslint/eslint-plugin": "^5.16.0",
     "@typescript-eslint/parser": "^5.16.0",
@@ -72,6 +71,8 @@
     "generate-license-file": "^1.3.0",
     "jest": "^28.1.0",
     "jest-environment-jsdom": "^28.1.0",
+    "rollup": "^3.29.1",
+    "rollup-plugin-typescript2": "^0.35.0",
     "ts-loader": "^8.4.0",
     "typescript": "^4.0.3",
     "webpack": "^5.73.0",