FIX for webpack: Export binary files in javascript package (#3085)

This adds the distributed binary files to the "exports" section of the package.json file. 
This allows the files to be referenced, e.g. by `require.resolve('pyodide/distutils.tar')`
which is useful for tools like webpack.

docs/project/changelog.md

@@ -44,6 +44,9 @@ substitutions:
   `indexURL` (this was a regression in v0.21.2).
   {pr}`3077`
 
+- {{ Enhancement }} Add binary files to exports in JavaScript package
+  {pr}`3085`.
+
 - {{ Enhancement }} Pyodide now works with a content security policy that
   doesn't include `unsafe-eval`. It is still necessary to include
   `wasm-unsafe-eval` (and probably always will be). Since current Safari

src/js/package.json

@@ -51,6 +51,11 @@
       "require": "./pyodide.js",
       "import": "./pyodide.mjs"
     },
+    "./distutils.tar": "./distutils.tar",
+    "./pyodide.asm.wasm": "./pyodide.asm.wasm",
+    "./pyodide.asm.js": "./pyodide.asm.js",
+    "./pyodide.asm.data": "./pyodide.asm.data",
+    "./pyodide_py.tar": "./pyodide_py.tar",
     "./pyodide.mjs": "./pyodide.mjs",
     "./pyodide.js": "./pyodide.js",
     "./package.json": "./package.json",