Add deprecation warning if v2 config detected

[eloquence]

Status

Ready for review

Description of Changes

Fixes #585. The warning is added to the validator, so it will also be displayed on the make validate target or manual invocation of the validation script.

Test plan

• Clone this branch to dom0.
• Ensure you have a valid v3 config under /usr/share/securedrop-workstation-dom0-config.
• Run python3 scripts/securedrop-admin.py --validate
• Observe that the configuration still validates without errors or warnings.
• Make a breaking modification to the .onion configuration (back up config as needed) and re-validate. For example, you could use an address of the wrong length.
• Observe that validation errors still get reported as exceptions
• Change the config to a correctly formatted v2 address.
• Observe that the configuration now validates successfully, but a deprecation warning is shown.

Checklist

• Linter (make flake8) passes in the development environment
• No packaging changes
• All tests (make test) pass in dom0 of a Qubes install [no current tests for this logic]

[emkll]

Thanks @eloquence. Functionally this works as expected, and while it's non blocking, should be sufficiently informative. The only change i would recommend here is inline

Tested as follows:

• Observe that the configuration still validates without errors or warnings.
• Make a breaking modification to the .onion configuration (back up config as needed) and re-validate. For example, you could use an address of the wrong length.
• Observe that validation errors still get reported as exceptions
• Change the config to a correctly formatted v2 address.
• Observe that the configuration now validates successfully, but a deprecation warning is shown.
• make test: all but one tests passed, encountered the issue described in sd-log sometimes ingests logs as host #583

[emkll]

thanks @eloquence