feat: support regexp output check for http/shell/ssh probe

[haoel]

• add an options regex:true|false to indicate the contain and not_contain is regexp or not.
• create a TextChecker object to dedicate the checker configuration and logic
• embed the TextChecker into HTTP/Shell/SSH probe

[proditis]

LGTM and tested

Adding the link here so that i can include details about the syntax on the extended documentation i'll work on https://github.com/google/re2/wiki/Syntax

[codecov-commenter]

Codecov Report

Merging #169 (4fcb696) into main (8b5be29) will increase coverage by 0.27%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #169      +/-   ##
==========================================
+ Coverage   93.15%   93.43%   +0.27%     
==========================================
  Files          46       46              
  Lines        3362     3411      +49     
==========================================
+ Hits         3132     3187      +55     
+ Misses        161      157       -4     
+ Partials       69       67       -2     

Impacted Files	Coverage Δ
probe/common.go	100.00% <100.00%> (ø)
probe/http/http.go	97.63% <100.00%> (+0.07%)	⬆️
probe/shell/shell.go	100.00% <100.00%> (ø)
probe/ssh/ssh.go	89.37% <100.00%> (+4.11%)	⬆️

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