Remove exceptions of Library rules

[BraisGabin]

We had this code to make our 3 library rules behave different. But our users don't understand that #3215.

With this PR I change those rules to behave as any other rule but changing their default configuration so the users can see what's going on.

This is an alternative implementation of #3279

I did disable the rule LibraryCodeMustSpecifyReturnType by default too.

[codecov]

Codecov Report

Merging #3304 (1e83ce9) into master (fb50099) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master    #3304   +/-   ##
=========================================
  Coverage     80.32%   80.33%           
+ Complexity     2721     2712    -9     
=========================================
  Files           445      445           
  Lines          8168     8171    +3     
  Branches       1553     1553           
=========================================
+ Hits           6561     6564    +3     
  Misses          774      774           
  Partials        833      833           

Impacted Files	Coverage Δ	Complexity Δ
...sch/detekt/rules/style/ForbiddenPublicDataClass.kt	89.47% <ø> (-0.53%)	11.00 <0.00> (-3.00)
...kt/rules/style/LibraryCodeMustSpecifyReturnType.kt	87.09% <ø> (-0.41%)	9.00 <0.00> (-3.00)
...kt/rules/style/LibraryEntitiesShouldNotBePublic.kt	83.33% <ø> (-0.88%)	7.00 <0.00> (-3.00)
.../detekt/generator/printer/rulesetpage/Exclusion.kt	96.66% <100.00%> (+0.83%)	0.00 <0.00> (ø)

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[schalkms]

I like this idea! The three rules changed their behavior, so this should be documented for the next release. Furthermore, I think all three rules could be activated by default.

[schalkms]

Maybe we should activate all three rules. With the exclude filter set by default nothing gets flagged, so this is fine.

[BraisGabin]

I activated them as you said but I'm not sure about this. This are rules only for library developers. Even if we exclude all the files it seems like rules that should be disabled by default.

[schalkms]

Let's see what the community thinks about it.

[schalkms]

@BraisGabin sorry for my late review. This PR went under my radar, unfortunately.

[schalkms]

All questions are solved. Thanks! PR looks good to me.

[BraisGabin]

Closes #3279

[arturbosch]

Should be clearer for the user, good thoughts!