Improve our Rollup config for server bundle to include wasp/ modules

[infomiho]

We bundle our server app to give users more freedom with how they write their imports paths i.e. they can use the .js suffix or can leave it out.

One thing we noticed is that in our bundle, the wasp/ package is not bundled and we have to copy over the Wasp SDK when building the server Docker image: #2362 (comment)

We are missing the@rollup/plugin-node-resolve plugin which enables Rollup to bundle packages from node_modules.

Here's a working rollup.config.js file that bundles the Wasp SDK:

import esbuild from 'rollup-plugin-esbuild'
import nodeResolve from "@rollup/plugin-node-resolve";

export default [
  createBundle('src/server.ts', 'bundle/server.js'),
  createBundle('src/dbSeed.ts', 'bundle/dbSeed.js'),
]

/**
 * @param {string} inputFilePath
 * @param {string} outputFilePath
 * @returns {import('rollup').RollupOptions}
 */
function createBundle(inputFilePath, outputFilePath) {
  return {
    input: inputFilePath,
    output: {
      file: outputFilePath,
      format: 'es',
      sourcemap: true,
    },
    plugins: [
      esbuild({
        target: 'esnext',
      }),
      // Using `modulesOnly` because I found it here: https://stackoverflow.com/questions/45707711/does-rollup-bundle-node-modules-into-bundle-js
      nodeResolve({
        modulesOnly: true
      })
    ],
    external: (id) => {
      // Anything that's not a relative or absolute import or a wasp/ module - should not be bundled e.g. Express won't be bundled
      return !id.startsWith('.') && !id.startsWith('/') && !id.startsWith('wasp/')
    },
    treeshake: 'smallest'
  }
}