Change obsreport helpers for receiver to use the same pattern as Processor/Exporter

[bogdandrutu]

• Define a struct and helpers similar with ProcessorObsReport (it will be renamed to just Processor)

[bhautikpip]

@bogdandrutu I could not find similar name pattern any more in any of the file in obsreport package. I also checked obsreport_receiver.go for more sanity. I think PR #2658 and #2657 covered most of the changes. Am I missing anything here?

[alolita]

@bogdandrutu is this still an open issue? Looks like the changes have already been made.

[bogdandrutu]

@bhautikpip those PRs are for exporters and processors, but for the Receiver/Scraper we have a completely different API that uses global functions instead of a per receiver object. So look at these APIs:

• Receiver https://github.com/open-telemetry/opentelemetry-collector/blob/main/obsreport/obsreport_receiver.go#L149
• Processor https://github.com/open-telemetry/opentelemetry-collector/blob/main/obsreport/obsreport_processor.go#L121

We need them to be consistent.

@alolita the work done was to improve processor and exporter but nothing done for the receiver/scraper.