feat: Add show_progress parameter for independent progress bar control

[aksg87]

Description

Adds show_progress parameter to control progress bar visibility independently of debug logging. Users can now show/hide progress without affecting debug output.

Fixes #221

Choose one: Bug fix

How Has This Been Tested?

# Formatted code
./autoformat.sh

# Linting passed
pylint --rcfile=.pylintrc langextract
pylint --rcfile=tests/.pylintrc tests

# Tests pass
pytest tests/init_test.py -k "test_show_progress" -v

All 4 parameterized test cases verify progress bar control works correctly.

Checklist:

• I have read and acknowledged Google's Open Source Code of conduct.
• I have read the Contributing page, and I either signed the Google Individual CLA or am covered by my company's Corporate CLA.
• I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach.
• I have made any needed documentation changes, or noted in the linked issue(s) that documentation elsewhere needs updating.
• I have added tests, or I have ensured existing tests cover the changes
• I have followed Google's Python Style Guide and ran pylint over the affected code.