New `exclude_regex` Filter to Address False Positives on Password Tests

Is your feature request related to a problem? Please describe.
Consistent issues arise on false positives of "token"-matched variable names in tests B105 and B106.

See: https://github.com/PyCQA/bandit/issues/498, https://github.com/PyCQA/bandit/issues/842, https://github.com/PyCQA/bandit/issues/843, https://github.com/PyCQA/bandit/issues/211

Describe the solution you'd like
It would be useful to have an exclude_regex field available to filter variable names, and not just excludes at the files and tests level.

Describe alternatives you've considered

• exclude and exclude_dirs skips entire files/folders and are too permissive
• skips completely skips entire tests and are too permissive
• # nosec entries clutter source code when there are excessive false positives

Additional context
Ideally, coupling an exclude_regex with exclude would be ideal granularity.

Example pyproject.toml to exclude "token" variable name filtering only in files under "tests/" folders for B106:

[tool.bandit.hardcoded_password_funcarg]
exclude_dirs = ["tests"]
exclude_regex = ["token"]

👍?

Start by tracing how exclude and exclude_dirs are handled for the B105 and B106 password checks, then inspect their existing tests and configuration handling. Add coverage for exclude_regex matching variable names while retaining file and test-level filtering, and verify the documented pyproject.toml example behaves as described.