feat(tools): replace npmignore with package.json#files within react-library generator

Author: Hotell

tools/workspace-plugin/src/generators/react-library/files/.npmignore__tmpl__

@@ -7,6 +7,7 @@
   "module": "lib/index.js",
   "typings": "./dist/index.d.ts",
   "sideEffects": false,
+  "files": ["lib", "lib-commonjs", "dist/*.d.ts"],
   "repository": {
     "type": "git",
     "url": "https://github.com/microsoft/fluentui"

tools/workspace-plugin/src/generators/react-library/files/package.json__tmpl__

@@ -53,7 +53,6 @@ describe('react-library generator', () => {
         "project.json",
         ".babelrc.json",
         ".eslintrc.json",
-        ".npmignore",
         ".storybook",
         ".swcrc",
         "LICENSE",
@@ -189,7 +188,6 @@ describe('react-library generator', () => {
         "project.json",
         ".babelrc.json",
         ".eslintrc.json",
-        ".npmignore",
         ".storybook",
         ".swcrc",
         "LICENSE",