Project linting: support for Python 3.14 and general cleanup

[asnare]

This PR upgrades the linting tools for the project: the previous versions did not work (and crashed) on Python 3.14 due to changes in the underlying bytecode format. Changes include:

• Upgrade mypy and pylint to their current versions.
• Fixing some type-annotation issues due to the linters being stricter.
• Updating some of the method signatures that changed in Python 3.13 but hadn't been updated, to keep the warnings from pylint across the different versions to a minimum.

None of the changes affect backward-compatibility with respect to using this package.

[codecov]

Codecov Report

❌ Patch coverage is 68.96552% with 27 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@ac509c1). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/databricks/labs/blueprint/paths.py	57.62%	14 Missing and 11 partials ⚠️
src/databricks/labs/blueprint/cli.py	92.59%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #319   +/-   ##
=======================================
  Coverage        ?   79.75%           
=======================================
  Files           ?       17           
  Lines           ?     2411           
  Branches        ?      521           
=======================================
  Hits            ?     1923           
  Misses          ?      361           
  Partials        ?      127           

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[github-actions]

✅ 40/40 passed, 2 skipped, 1m40s total

_{Running from acceptance #372}

[asnare]

This was dropped because the option is no longer supported by pylint. (Version 4+ always behaves as if this option is on.)