Prepare repository for next .github release and SBT build improvements

[alejandrohdezma]

What has been done in this PR?

Prepare project for next .github release

• Add ci-publish command alias that will be used instead of ci-release for publishing artifacts.
• Move docs templates to docs folder (as mdoc is expected).
• Move microsite files to microsite folder.
• Run github before ci-docs & ci-publish.
• Remove ci-microsite (it gets inline in ci-docs).
• Add actions.yml file that will be used by next .github release workflows to read pre/post conditions to run before/after ci-* commands.

Simplify SBT build

• Re-order settings.
• Remove unneeded settings & plugins.
• Remove old sbt-org-policies markers.
• Add sbt-remove-test-from-pom to avoid publishing test dependencies to POM.
• Add sbt-codecov to run tests with coverage and auto-upload to Codecov.

Update versions

• Update plugins to latest versions
• Update Scala version

[codecov]

Codecov Report

Merging #143 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #143   +/-   ##
=======================================
  Coverage   43.28%   43.28%           
=======================================
  Files          11       11           
  Lines         201      201           
  Branches        6        5    -1     
=======================================
  Hits           87       87           
  Misses        114      114           

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