Add ExecTask suggestions

[jawira]

Display a suggestion when the executable from ExecTask can be replace by a Task.

[jawira]

I think code is good to go, but I'm waiting your feedback.
I will add some tests in coming days.

[codecov]

Codecov Report

Merging #1643 (def495e) into main (d482e37) will increase coverage by 0.03%.
The diff coverage is 64.70%.

@@             Coverage Diff              @@
##               main    #1643      +/-   ##
============================================
+ Coverage     58.19%   58.22%   +0.03%     
- Complexity     6964     7010      +46     
============================================
  Files           356      356              
  Lines         16862    16947      +85     
============================================
+ Hits           9813     9868      +55     
- Misses         7049     7079      +30     

Impacted Files	Coverage Δ
src/Phing/Task/System/ExecTask.php	80.00% <64.70%> (-6.67%)	⬇️

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