Mvc\Micro cleanup and setModelBinder() fix

[SidRoberts]

Hello!

• Type: bug fix | code quality
• Link to issue:

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

Also fixed a small bug whereby calling setModelBinder() without explicitly setting a DI first could cause problems.

[codecov]

Codecov Report

Merging #14171 into 4.0.x will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##            4.0.x   #14171      +/-   ##
==========================================
+ Coverage   74.56%   74.56%   +<.01%     
==========================================
  Files         455      455              
  Lines       94411    94429      +18     
==========================================
+ Hits        70394    70414      +20     
+ Misses      24017    24015       -2

Impacted Files	Coverage Δ
ext/phalcon/mvc/micro.zep.c	81.42% <0%> (+0.49%)	⬆️

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[niden]

Thank you @SidRoberts