Refactor the Remote Configuration (RC) as a standalone module, enabling
its use independently of the tracer. Additionally, ensure that external
listeners can register and receive configuration updates when RC is
embedded in the tracer.

Changes:
  - Move APM_TRACING updates handling to the configuration manager.
  - Expose the `remote_configuration_listeners` field in datadog agent config
    to allow registration of external listeners.
  - Improve the robustness of config path parsing and ensure an error is reported
    if parsing fails.
  - Add `to_upper` utility function.
  - Increase test coverage for RC and the new configuration manager
    behaviour.

dmehala deleted the dmehala/remote-config-module branch

dmehala added a commit that referenced this pull request

Resolve a regression introduced in #130 where the `configuration_change`
payload didn't adhere to the telemetry schema.

dmehala added a commit that referenced this pull request

Resolve a regression introduced in #130 where the `configuration_change`
payload didn't adhere to the telemetry schema.