[receiver] Move scraper packages into scraper module

[mx-psi]

We have two packages, scrapererror and scraperhelper that are part of the receiver module, but are not necessary for Collector v1 (we only intend to stabilize the OTLP receiver at first).

We can make a new receiver/scraper module that has these two as packages. This would reduce the API surface that we have to stabilize.

[mx-psi]

As an example of a PR adding a new module, see #11000.

[zhengkezhou1]

Hi @mx-psi , i would like to try.

[mx-psi]

@zzzk1 Please give it a try! :)