create dist script with npm and gltf-transform

[kfarr]

today we create draco compressed glb files using a few different methods, depending on who is converting them. this is done in a separate repo and requires manual commits.

instead, it would be time saving for 3d modelers to only edit files on this source repo and then run a script such as npm run dist that runs a command line tool to convert gltf files into the desired lower quality compression. It could be done with this tool for example: https://gltf-transform.donmccurdy.com/cli.html . Commits to source repo should trigger a github ci action to run the dist script which builds to a dist branch. The assets subdomain (https://assets.3dstreet.app/) should instead resolve to this automatically building branch.

pros/cons:

• there could be a "failing" build, how to handle? are there tests?
• to maintain the dual directory structures, it might be necessary to have a mapping between source directory and dist directory?
• alternatively, the directory structure doesn't have a lot of inherent utility, so we could just use the same paths as source and copy them as-is into dist and update paths in 3dstreet core assets.js

[kfarr]

cc @mwbeene would love to get your feedback on the above