fix(remix): Sourcemaps upload script is missing in the tarball (#5356)

Add the sourcemaps upload script to the tarball, which required the following changes:
* Add a package-specific `prepack.ts` script which is invoked by the main `prepack.ts` script. This is similar to how we do it with the Gatsby SDK where - just as with Remix - we need to copy over additional files to the `build` directory that are not part of our other packages. The newly added files are:
  * `scripts/sentry-upload-sourcemaps.js`
  * `scripts/createRelease.js`
* Add a package-specific `.npmignore` which extends the root level `.npmignore` file to not ignore the `scripts` directory in the `build` directory.

packages/remix/.eslintrc.js

@@ -10,4 +10,12 @@ module.exports = {
   rules: {
     '@sentry-internal/sdk/no-async-await': 'off',
   },
+  overrides: [
+    {
+      files: ['scripts/**/*.ts'],
+      parserOptions: {
+        project: ['../../tsconfig.dev.json'],
+      },
+    },
+  ],
 };

packages/remix/.npmignore

@@ -0,0 +1,4 @@
+# The paths in this file are specified so that they align with the file structure in `./build` after this file is copied
+# into it by the prepack script `scripts/prepack.ts`.
+
+!/scripts/**/*

packages/remix/scripts/prepack.ts

@@ -0,0 +1,34 @@
+/* eslint-disable no-console */
+
+import * as fs from 'fs';
+import * as path from 'path';
+
+const PACKAGE_ASSETS = ['scripts/sentry-upload-sourcemaps.js', 'scripts/createRelease.js'];
+
+export function prepack(buildDir: string): boolean {
+  // copy package-specific assets to build dir
+  return PACKAGE_ASSETS.every(asset => {
+    const assetPath = path.resolve(asset);
+    const destinationPath = path.resolve(buildDir, asset);
+    try {
+      if (!fs.existsSync(assetPath)) {
+        console.error(`\nERROR: Asset '${asset}' does not exist.`);
+        return false;
+      }
+      const scriptsDir = path.resolve(buildDir, 'scripts');
+      if (!fs.existsSync(scriptsDir)) {
+        console.log('Creating missing directory', scriptsDir);
+        fs.mkdirSync(scriptsDir);
+      }
+      console.log(`Copying ${path.basename(asset)} to ${path.relative('../..', destinationPath)}.`);
+      fs.copyFileSync(assetPath, destinationPath);
+    } catch (error) {
+      console.error(
+        `\nERROR: Error while copying ${path.basename(asset)} to ${path.relative('../..', destinationPath)}:\n`,
+        error,
+      );
+      return false;
+    }
+    return true;
+  });
+}