Move receiver into an internal package, in preparation for profiles

[dmathieu]

Description

This splits the receiver package, so the APIs are in an internal package, and redefined publicly for logs/metrics/traces.
In preparation for adding profiles to the package.

Link to tracking issue

See #10375

cc @mx-psi

[codecov]

Codecov Report

Attention: Patch coverage is 98.90110% with 1 line in your changes missing coverage. Please review.

Project coverage is 92.40%. Comparing base (9405cfe) to head (7409c0a).

Files	Patch %	Lines
receiver/internal/factory.go	97.77%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10530   +/-   ##
=======================================
  Coverage   92.39%   92.40%           
=======================================
  Files         393      395    +2     
  Lines       18614    18622    +8     
=======================================
+ Hits        17199    17207    +8     
  Misses       1058     1058           
  Partials      357      357           

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