fix: import yargs/yargs in esm projects (#2151)

package.json

@@ -22,6 +22,7 @@
     },
     "./yargs": [
       {
+        "import": "./yargs.mjs",
         "require": "./yargs"
       },
       "./yargs"

yargs.mjs

@@ -0,0 +1,10 @@
+// TODO: consolidate on using a helpers file at some point in the future, which
+// is the approach currently used to export Parser and applyExtends for ESM:
+import pkg from './build/index.cjs';
+const {applyExtends, cjsPlatformShim, Parser, processArgv, Yargs} = pkg;
+Yargs.applyExtends = (config, cwd, mergeExtends) => {
+  return applyExtends(config, cwd, mergeExtends, cjsPlatformShim);
+};
+Yargs.hideBin = processArgv.hideBin;
+Yargs.Parser = Parser;
+export default Yargs;