In this PR we introduce the API that will expose the global retention configuration and will allow users to take advantage of it.
These APIs are protected by the dedicated introduced privileges:
`manage_data_stream_global_retention` or higher, which allows all operations on the global retention configuration
`monitor_data_stream_retention` or higher, which allows the retrieval of the global retention configuration.
This PR is the final PR that makes the global retention available for our users.
