Optimize JS bundles

Related to https://github.com/matrix-org/matrix-public-archive/issues/132

Bundle efficiency

Based on what I was seeing in https://github.com/matrix-org/matrix-public-archive/pull/175 trying to get the bundles to work; I couldn't properly get the chunks working as I ideally wanted where each entry point would be bundled up with no chunks except for a vendor chunk that included hydrogen-view-sdk

And I know the current chunking makes entry-client-room-alias-hash-redirect.js inefficient by just making it small and pulling in a separate redirect-if-room-alias-in-hash chunk which seems completely unnecessary and could be bundled into itself without an extra import.

Any combination of manualChunks and experimentalMinChunkSize options I tried with Vite just didn't do the trick.

Also see https://vitejs.dev/guide/build.html#chunking-strategy

Bundle size

The bundles seem pretty big at the moment and there is probably lots of opportunity to prune things down. Are we even tree-shaking?

Hopefully in https://github.com/matrix-org/matrix-public-archive/pull/175, we figure out how to minify the JS.

Dev notes

A way to visualize JS bundles:

• DevTools: A better to way to visualize your JavaScript, https://umaar.com/dev-tips/270-devtools-lighthouse-treemap/ (direct link to YouTube)

Start with Vite's chunking strategy documentation and the current build configuration, then inspect the entry-client-room-alias-hash-redirect.js entry point and its redirect-if-room-alias-in-hash chunk. Compare the generated bundles for unnecessary chunks, minification, and tree-shaking; done means a documented, measured reduction in unnecessary chunks and bundle size.