fix: expose escape_html param to DoclingDocument md serialization

[ceberam]

This PR add a flag in the serialization of a DoclingDocument into markdown format to decide whether to escape reserved HTML characters (default) or not.

Resolves #387

[github-actions]

✅ DCO Check Passed

Thanks @ceberam, all your commits are properly signed off. 🎉

[dosubot]

Related Documentation

Checked 2 published document(s). No updates required.

^{You have 5 draft document(s). Publish docs to keep them always up-to-date}

^{How did I do? Any feedback?}  

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[mergify]

Merge Protections

Your pull request matches the following merge protections and will not be merged until they are valid.

🟢 Enforce conventional commit

Wonderful, this rule succeeded.

Make sure that we follow https://www.conventionalcommits.org/en/v1.0.0/

• title ~= ^(fix|feat|docs|style|refactor|perf|test|build|ci|chore|revert)(?:\(.+\))?(!)?:

[dolfim-ibm]

lgtm

[PeterStaar-IBM]

lgtm!

[dosubot]

Documentation Updates

Checked 2 published document(s). No updates required.

^{You have 5 draft document(s). Publish docs to keep them always up-to-date}

^{How did I do? Any feedback?}