T3135 best language

[niden]

Hello!

• Type: new feature
• Link to issue: [NFR] allow Request::getBestLanguage() to return language without dialect #3135

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Added Phalcon\Http\Request::getBestLanguageIso() to return the base language if this is a specific one (en vs en-US)

Thanks

[codecov]

Codecov Report

Merging #14698 into 4.1.x will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##            4.1.x   #14698      +/-   ##
==========================================
+ Coverage   67.75%   67.76%   +<.01%     
==========================================
  Files         480      480              
  Lines      111629   111654      +25     
==========================================
+ Hits        75637    75662      +25     
  Misses      35992    35992