Setup basic structure for CTest, create test placeholder in each project, start creating some tests. Closes #74 👍

• Refine project directory structure to better fit CTest( in app projects move code under src; keep config at root level; move public capturelib to reprostim namespace/folder; create test folder in each subproject dedicated to test, and keep each test closer to project and source code), so it will look close to this picture:
  
• Start implementing simple CTest with CMake (e.g. run --help for reprostim-*capture utilities).
• Research and create simple unit test starter examples in capturelib for few APIs, consider catch2 or gtest as start point.
• Integrate tests with github workflow.
• Add notes in Capture/README.md regarding testing with CTest.