perf: enable code splitting in build process

[RyukTheCoder]

Summary

Enabled code splitting in build options of esbuild. Code splitting is still a work in progress in esbuild docs because it only works with esm output format (which we currently use) and it has a known ordering issue. I'm not sure if we may encounter that issue but the is a workaround introduced to prevent that. You can follow the tracking issue for updates about this feature.

After applying this change and testing it through linking widget-embedded package in app repo, I observed that bundle size is reduced to 1.4MBs.

Fixes # 1905

How did you test this change?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Implemented a user interface (UI) change, referencing our Figma design to ensure pixel-perfect precision.

[yeager-eren]

lgtm