fix: escape headers and unordered lists in markdown utils

[onerandomusername]

Summary

Expanded markdown support in remove markdown and escape markdown methods. This does not currently support ordered lists, unfortunately.

Checklist

• [x] If code changes were made, then they have been tested
  • [ ] I have updated the documentation to reflect the changes
  • [x] I have formatted the code properly by running pdm lint
  • [x] I have type-checked the code by running pdm pyright
• [ ] This PR fixes an issue
• [ ] This PR adds something new (e.g. new method or parameters)
• [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed)
• [ ] This PR is not a code change (e.g. documentation, README, ...)

[onerandomusername]

This replaces # and - anywhere in a string, not only at the start of a line

Seems like something that could use a bunch of testing, so moving it to the next version might make sense here.

Sigh, that's fair. Possibly can be part of a bugfix release, like 2.9.1

[onerandomusername]

Due to more quirks with the client this entire implementation is wrong.