Fix UnicodeEncodeError in CLI docs on non-UTF consoles

[RedZapdos123]

Changes done:

Fixes a CLI crash when printing provider docs to terminals using non-UTF encodings (for example cp950 on Windows).

Problem Explaination:

python -m faker can raise UnicodeEncodeError while printing provider examples that include characters unsupported by the output encoding (such as emoji on cp950).
This happens in print_provider() when writing formatted documentation lines.

Fix:

• Adds _encode_for_output() in faker/cli.py to safely encode output strings for the active stream encoding.
• Falls back to backslashreplace when characters are not encodable, so output remains printable and the CLI does not crash.
• Uses this safe encoding path for provider headings and example lines printed by print_provider().
• Adds regression test test_print_provider_handles_non_utf_output to verify cp950 output no longer crashes and preserves escaped content.

Fixes #2361

AI Assistance Disclosure (as REQUIRED):

• No AI tools were used in preparing this PR.
• If AI tools were used, I have disclosed which ones, and fully reviewed and verified their output.

AI tool used: GitHub Copilot (GPT-5.3-Codex), used for code drafting and test drafting. All changes were manually reviewed and validated by running tests.

Checklist:

• I have read the documentation about CONTRIBUTING.
• I have read the documentation about Coding style.
• I have run make lint.

The screenshots of the tests run, for validation (ran on WSL):