otel: add attributes to all calls: project_name and is_user_service

[deniseli]

project_name: from ftl-project.toml

is_user_service: We have the serviceName set here, which currently will be one of ftl-controller, ftl-runner, or <module name>. Technically, we could use ftl-controller || ftl-runner but it would be good to be a bit more explicit.

• To do this, add bool flag IsInternal to observability.Config so that Init’s callers can configure whether it’s user code or not.
• Naming: is_user_service, is_internal, or similar are all fine