Initial l10n / multilanguage support

[kdmukai]

Description

This is a MASSIVE refactor. Apologies to all!!

(this description is still a work-in-progress; more details will be added before this DRAFT PR is flipped to Ready for Review)

Review the new l10n/README.md to get the basics of how the translations are implemented. The biggest key is that we have to be a bit savvy about TWO distinct (yet often overlapping) translation-related tasks:

1. Mark a string literal as needing translation. This gets it added to Transifex for translators to work on.
2. Retrieving the translation for either an English string literal OR a string held in a variable.

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New:

• Submodule dependency on the new seedsigner-translations repo.

• ButtonOption class to manage View.button_data entries. Allows us to preserve the existing approach of using class-level attrs to indicate user options in a View (e.g. MainMenuView.TOOLS vs MainMenuView.SCAN). It's wired up to mark the user-facing button labels as needing translation. But never translates those values based on locale (that happens later in the Screen classes; we need these class-level attrs to remain untranslated). Bonus: cleans up some sloppy tuple-based code in those attrs and enables some nicer handling (see its return_data field).

• seedsigner.helpers.l10n.mark_for_translation: you'll see this imported as _mft and used for any class-level attr that isn't already covered by the ButtonOption above (e.g. a class-level display field like title that has an English literal string). As far as the translation handling goes, it behaves the same as ButtonOption: mark it for translation, but do not provide the translated version.

• Screenshot generator made l10n aware, generates screenshots in each supported language.

  • Better integration with pytest: dynamically considers each locale as a separate test to report progress on.
  • Dynamically sets pytest.skip for deactivated locales when the optional --locale command line arg is present.
  • Added some screenshots that were previously missing, various screenshot generation tweaks.

• TopNav scrollable titles via updated TextArea component. Autoscrolls if the title is too long to display.

  • ScrollableTextLine added as a convenience class that's really just a scrolling single line TextArea.

• Simplified python-babel CLI commands via setup.py and setup.cfg.

  • python-babel does not have pyproject.toml integration, unfortunately. So setup.py is back in skeleton form to enable the CLI convenience; the simplicity of python setup.py extract_messages is worth some extra project file cruft.
  • setup.cfg contains all the configuration for the extract_messages and compile_catalog integrations we need.

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misc:

• Adds tests/run_full_coverage.sh convenience script to generate local code coverage reports that combine the results from the test suite and the screenshot generator.
• Slightly expanded coverage file filtering in pyproject.toml to account for the additional GUI / Screen coverage provided by the screenshot generator.
• CI update to recursively fetch submodules when setting up the test runner (has to pull in the seedsigner-translations repo as a submodule for the new l10n tests to pass).
• CI update to combine coverage reports for both the test suite and the screenshot generator.
• Some import refactoring to hide our module imports whenever possible (moves the imports to within their calling functions). Not really necessary, just trying to minimize imports at the top of each file.

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This pull request is categorized as a:

• New feature
• Code refactor
• Documentation
• Ginormous whale

Checklist

• I’ve run pytest and made sure all unit tests pass before sumbitting the PR

If you modified or added functionality/workflow, did you add new unit tests?

• Yes

I have tested this PR on the following platforms/os:

• Raspberry Pi OS Manual Build
• SeedSigner OS on a Pi0/Pi0W board

[jdlcdl]

Working on a new pi02w development board, have tried up to 80ea2cb but need to review code changes since last review.