Add option to Core settings to enable duplicated logs

[sairon]

Proposed change

Introduce new option duplicate_log_file to HA Core configuration that will set an environment variable HA_DUPLICATE_LOG_FILE=1 for the Core container if enabled. This will serve as a flag for Core to enable the legacy log file, along the standard logging which is handled by Systemd Journal.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality to the supervisor)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Document duplicate_log_file Core option developers.home-assistant#2888
• Link to cli pull request: Add --duplicate-log-file Core option cli#618
• Link to client library pull request: Add duplicate_log_file Core option home-assistant-libs/python-supervisor-client#228

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Ruff (ruff format supervisor tests)
• Tests have been added to verify that the new code works.

If API endpoints or add-on configuration are added/changed:

• Documentation added/updated for developers.home-assistant.io
• CLI updated (if necessary)
• Client library updated (if necessary)