feat: Add boilerplate unit test framework and GitHub workflows for automated testing.

[Bill-hbrhbr]

Description

• Adds Catch2 submodule
• Adds function cpp_test() to specify the test files to include and the dependencies they need for each library.
• Replace the dummy build target with a proper unitTest target.
• Add Taskfile workflow build:run-all-tests to run unit tests.
• Update the Github workflow to run the new Taskfile workflow.

Validation performed

• New workflows for unit tests succeed.