Not caching tilesets from local file URL?

[nithinp7]

I haven't looked into this too deeply just yet, so this may not be completely accurate.

I was testing a glTF feature in a Cesium Native integration by hacking together a local tileset.json to wrap a simple glTF. While I was fixing up the bounding volumes / geometric error in the tileset.json to have the model render sensible, I realized that updates I made in the tileset.json were being properly reflected if I refreshed the tileset! While this was convenient for what I was doing, it made me wonder if something's wrong with how we are caching local file url requests - perhaps the way we look for cache directives / expiry times or something is causing these requests (or at least the tileset.json request) to not be cached?

Although the asset accessor is a client implementation detail, there may be something we should tweak in Cesium Native to treat local file urls separately. I've noticed this in two separate Cesium Native integrations so far, fwiw. I'll look into this deeper when I have time to circle back (probably as part of #569).