version up KMP to 2.1

[jsoizo]

• Update KMP version to use the latest features.
• Remove java Gradle plugin because it is incompatible with the KMP plugin
• Replace JaCoCo with kotlinx-kover since JaCoCo requires the Java plugin

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.98%. Comparing base (7198928) to head (0c842e4).
Report is 4 commits behind head on version_2_0_0.

Additional details and impacted files

@@                 Coverage Diff                 @@
##             version_2_0_0     #153      +/-   ##
===================================================
+ Coverage            86.66%   91.98%   +5.32%     
===================================================
  Files                   21       12       -9     
  Lines                 1282      337     -945     
  Branches               192       74     -118     
===================================================
- Hits                  1111      310     -801     
+ Misses                  32       13      -19     
+ Partials               139       14     -125     

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