chore: Add Catch2 dependency and manage its installation with Taskfile workflows.

[Bill-hbrhbr]

Description

• Download and install Catch2 dependency with the newest cmake and remote tasks in yscope-dev-utils.
• Replace the current cmake config and build tasks in ystdlib-cpp with the newest versions in yscope-dev-utils.
• Change the dummy target to a Catch2 unit test target.
• Ensure all tasks have specified the correct sources, generates, and status to preserve necessary re-runs and prevent unnecessary runs.
• Remove submodules as a potential folder to exclude when linting yaml files in ystdlib-cpp. Now every non-project file resides in build except for yscope-dev-utils.
• Update the lint:venv task to comply with the arglist of new checksum tasks in yscope-dev-utils.

Most importantly: the highest-order-bit task build:all should trigger a re-run whenever there's a dependency change.

Checklist

• The PR satisfies the contribution guidelines.
• This is a breaking change and that has been indicated in the PR title, OR this isn't a
  breaking change.
• Necessary docs have been updated, OR no docs need to be updated.

Validation performed

• The new unit test target builds and runs succcessfully.