Prevent inline formatting inside inline code

[shriram-svg]

Summary

• strip inline formatting token classes when BFM/CodeMirror already marks a token as code
• add a BFM runMode regression for multiline inline-code highlighting with asterisks inside the code span

Fixes #2251.

Verification

• npx --yes -p node@20 node node_modules/jest/bin/jest.js tests/lib/bfm.test.js --runInBand --testURL=http://localhost
• npx --yes -p node@20 node node_modules/eslint/bin/eslint.js tests/lib/bfm.test.js
• git diff --check
• CodeMirror 5.40.2 lockfile reproduction script: bad code-token count is 0 after this patch

Note: extra_scripts/codemirror/mode/bfm/bfm.js is skipped by the repository ESLint ignore pattern; forcing ESLint on that legacy file reports pre-existing project style errors.