Add collector confmap providers to the registry

[svrnm]

I think confmap providers should be added to the registry: they are conceptually similar to other kinds of components in the Collector in that they provide extra functionality to the Collector, can be added on a Collector builder manifest, can be 'official' or come from a third-party repository...

Originally posted by @mx-psi in #5363 (comment)

[jackgopack4]

we also have added the ability to specify custom confmap converters with the latest release of v0.114.0 OpenTelemetry Collector Builder tool; I think it would make sense to add this type as well