Improve obtaining arguments in generic classes

[alexander-yevsyukov]

This PR makes it easier to obtain a generic type argument in both Java and Kotlin code.

Changes in details

• The method called argumentIn() of the Java utility class Types was made public. Previously it was package-private.
• The order of parameters of the method was improved to 1) match the name 2) reduce the change of accidental misplacement of Class arguments.
• The extension function called argumentIn() for Class was added to make it more natural when working from Kotlin.

[armiol]

@alexander-yevsyukov LGTM with a minor comment.

[armiol]

This line is redundant.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.82%. Comparing base (34572e7) to head (187544b).

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #10      +/-   ##
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+ Coverage     85.67%   85.82%   +0.14%     
- Complexity      102      104       +2     
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  Files            13       13              
  Lines           391      395       +4     
  Branches         44       46       +2     
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+ Hits            335      339       +4     
  Misses           44       44              
  Partials         12       12