Too confusing to have `MetadataList` and `ListMetadata`, etc.
I standardised on the ones which are in an interface.
Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
* A registerer is passed to the scrape Manager,
and all scrape metrics register with it.
* For now the registry which we pass to the scrape
Manager is still the global one.
Signed-off-by: Paulin Todev <paulin.todev@gmail.com>