split workflows

[eahenle]

• splits GitHub Actions workflows.
• CI_Build workflow runs on pushes & PRs vs. master branch. Includes unit tests, doc tests, Aqua.
• doc_deployment workflow runs on master branch commits.
• nightly workflow runs on regular schedule. Tests cross-platform builds.

[codecov-commenter]

Codecov Report

Merging #218 (1321157) into master (3a0ac8e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #218   +/-   ##
=======================================
  Coverage   57.11%   57.11%           
=======================================
  Files          15       15           
  Lines        1378     1378           
=======================================
  Hits          787      787           
  Misses        591      591           

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[eahenle]

@SimonEnsemble ready to merge