take over AWS Sumerian code so we can manage dependencies, update Three.js, to enable making new features in a scalable way.

[trusktr]

Rather than copy/pasting a build file into the repo, bring in AWS Sumerian code into the repo and own it.

Then we can update Three.js and make sure it matches between both the Sumerian code and Lume, etc.

This will allow us to develop further features in an easy way.

Optionally, rather than bringing in the code, we could keep it in our fork of the sumerian repo that we manage in our own way, so we can easily update it and consume it.

WIP:

• [ ] https://github.com/aws-samples/amazon-sumerian-hosts/issues/182 -- This greatly reduces maintenance burden for amazon-sumerian-hosts.
• [ ] https://github.com/aws-samples/amazon-sumerian-hosts/issues/155 -- For completeness sake, we can't own the amazon-sumerian-hosts code until we fix this one issue with Babylon (even though we're not currently using Babylon, but with due time will make this high usable with the main three web rendering systems)

[trusktr]

I'm currently unblocking this by fixing the Babylon.js issue in amazon-sumerian-hosts. We're not currently using Babylon.js (we could in the future), but various people that are following amazon-sumerian-hosts are interested in the Babylon fix. So unblocking them will potentially bring in more people once we publish Autonomys as a showcase using amazon-sumerian-hosts, and those people may also be able to replicate what we did with Lume/Three.js using Babylon, to help provide an alternative for the Babylon ecosystem!