Add __init__.py files to convert the folders to python module.

[yegle]

Description

This allows one to run pytest in the root folder to trigger all the tests, instead of needing to modify PYTHONPATH environment variable.

Checklist

General

• Added the correct label
• Assigned to a specific person or civiform/deployment-system
• Created tests which fail without the change (if possible)
• Performed manual testing (at a minimum run bin/setup without your changes and then bin/deploy with your changes to ensure your changes don't break existing deployments)
• Extended the README / documentation, if necessary

Instructions for manual testing

Local test passes:

(venv) ych@penguin ~/git/cloud-deploy-infra (git)-[pytest-fix]-
$ pytest 
=================================== test session starts ===================================
platform linux -- Python 3.11.2, pytest-8.3.2, pluggy-1.5.0
rootdir: /home/ych/git/cloud-deploy-infra
collected 59 items                                                                        

cloud/aws/bin/pgadmin_test.py ..................                                    [ 30%]
cloud/shared/bin/lib/check_test.py .                                                [ 32%]
cloud/shared/bin/lib/config_loader_test.py ...............                          [ 57%]
cloud/shared/bin/lib/config_parser_test.py ...                                      [ 62%]
cloud/shared/bin/lib/variable_definition_loader_test.py .                           [ 64%]
cloud/shared/bin/lib/write_tfvars_test.py ...                                       [ 69%]
cloud/shared/validate_variable_definitions_test.py ..................               [100%]

=================================== 59 passed in 1.07s ===================================

Issue(s) this completes