feat(scala): Add WriteAPI for Scala

[bednar]

Closes #125

Proposed Changes

Added WriteAPI for Scala.

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• mvn test completes successfully
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #347 (026ba19) into master (19cf00f) will increase coverage by 0.08%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master     #347      +/-   ##
============================================
+ Coverage     88.88%   88.97%   +0.08%     
- Complexity      633      634       +1     
============================================
  Files           153      155       +2     
  Lines          6282     6330      +48     
  Branches        302      302              
============================================
+ Hits           5584     5632      +48     
  Misses          612      612              
  Partials         86       86              

Impacted Files	Coverage Δ
...cala/com/influxdb/client/scala/WriteScalaApi.scala	100.00% <100.00%> (ø)
...lient/scala/internal/InfluxDBClientScalaImpl.scala	100.00% <100.00%> (ø)
...uxdb/client/scala/internal/WriteScalaApiImpl.scala	100.00% <100.00%> (ø)

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