Convert Markdown P2 itest to Repo and Include as Submodule

1. Create a new BB project "Testing" and repo "markdown-test"
2. Copy contents of P2 markdown app's ../src/itest into the new repo
3. Create README with instructions on how to add/use the repo and its purpose.
4. Under this issue branch impl the new repo as a submodule in confluence-markdown-connect

Instructions on how this is done: https://share.vidyard.com/watch/ewHt2EE4jiwVFk1tJoHtFz?

5. Analyze and harmonize the differences between P2 and Connect apps' .../src/itest content
6. Create issue for P2 app to convert to submodule as well.