Add black and ruff to fix lint/pep/ and other issues automatically

[shhovhan]

Summary

This PR modernizes and stabilizes the linting and formatting pipeline while keeping OpenStack standards.

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What Was Done

• Integrated Ruff for:

  • Import sorting
  • Unused import removal
  • General lint auto-fixes (E, F, I rules)

• Integrated Black as the canonical code formatter (default line length = 88)

• Kept flake8 + hacking to enforce OpenStack-specific standards

• Kept doc8 for documentation validation

• Updated tox configuration:

  • pep8 environment → CI check-only (no file modifications)
  • fix-pep8 environment → local auto-fix (modifies files)

• Disabled E501 and E203 in flake8 to avoid conflicts with Black formatting (as recommended by Black documentation)

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Why to much files changed

The large diff is intentional.

Black reformatted the entire codebase to a consistent style:

• Normalized indentation
• Adjusted line wrapping (88 characters)
• Standardized slice spacing
• Reformatted long imports
• Removed trailing whitespace
• Applied consistent multiline formatting

Ruff additionally:

• Removed unused imports
• Sorted imports
• Cleaned up minor style inconsistencies

No functional or behavioral changes were introduced.
All changes are formatting and lint normalization only.

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Why This Is Beneficial

• Eliminates inconsistent formatting across the repository
• Reduces CI noise caused by minor style differences
• Aligns with modern Python tooling practices
• Provides a single command to auto-fix issues locally

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CI Behavior

CI now runs linting in read-only mode.
If formatting is incorrect, CI fails without modifying files.

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Impact

• No runtime changes
• No API changes
• No test logic changes
• Formatting and lint normalization only

[otc-zuul]

Build succeeded.
https://zuul.otc-service.com/t/eco/buildset/cb30e0228ba8479da99b17368b19898e

✔️ test-release SUCCESS in 3m 46s
✔️ otc-tox-docs SUCCESS in 14m 57s
✔️ build-otc-releasenotes SUCCESS in 4m 36s
✔️ otc-tox-py310 SUCCESS in 4m 41s
✔️ otc-tox-pep8 SUCCESS in 3m 23s
✔️ tox-functional-eu-de SUCCESS in 16m 22s
✔️ otce-upload-image SUCCESS in 4m 04s