[confighttp, configgrpc] Replace host parameter by map of extensions

[jade-guiton-dd]

Description

Alternative to #14162, where we make the map of extensions a mandatory positional parameter to replace host instead of an option.

Link to tracking issue

Fixes #13640

Testing

Existing tests make extensive use of the modified functions

Documentation

Added line in ToServer/ToClient(Conn) documentation describing the intended use of the extensions parameter.

[codecov]

Codecov Report

❌ Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 92.14%. Comparing base (587a7d2) to head (ec678bd).

Files with missing lines	Patch %	Lines
receiver/otlpreceiver/otlp.go	50.00%	0 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (94.73%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14190      +/-   ##
==========================================
+ Coverage   92.13%   92.14%   +0.01%     
==========================================
  Files         666      666              
  Lines       41438    41437       -1     
==========================================
+ Hits        38180    38184       +4     
+ Misses       2218     2215       -3     
+ Partials     1040     1038       -2     

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