Ability to specify per-tileset request headers + helper for Basic Authentication

[Sean Lilley]

I'm trying to load a tileset from a server that uses basic authentication for all HTTP requests. I was able to modify cesium-omniverse to add the authentication header (see code below), but it would be convenient to have functionality like this built in to cesium-native, i.e. the ability to specify per-tileset request headers + a helper for basic authentication.

session->SetAuth(cpr::Authentication{"username", "password", cpr::AuthMode::BASIC});

This was also requested on the forum: https://community.cesium.com/t/3d-tileset-from-url-basic-authentication/21974