Create initialized sites subdirectory

Summary:
Database files for initialized sites should be store in an existing
directory, service create only the database directory itself.

The content of the ensure_parent_directory_exists has been wrote
by ChatGPT, as part of an experiment to evaluate suitability to help
to write, review bugs and development. This is a trivial case where
it succeeds to write the body of a method given its signature.

Test Plan:

• Delete initialized, run alkane deploy
• Run it again
• Create initialized as a file

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D3016