refactor: extract worker template and get rid of icij-worker dependency

[ClemDoum]

Changes

.testcontainers,docker-compose

Changed

• moved test containers assets/resources into .testcontainers
• updated temporal testconainter configuration consistently with https://github.com/ICIJ/datashare/tree/main/.devcontainer (ideally we'd like to use the exact samed containers, left for later...)

datashare-python

Removed

• remove task and workflow examples and moved them the worker-template

Changed

• removed any dependency to icij-worker by moving useful logic in datashare-python (mainly in utils and objects)

Changed

• refactored/simplified dependency injection to rely on the standard lib AsyncExitStack and ContextVars

.github

Added

• added ruff based linting test for worker-template and datashare-python