Add a yara operator

[mavam]

This PR adds a yara operator that makes it possible to match YARA rules on byte chunks.

### Tasks
- [x] Implement the `yara` operator
- [x] Add docs
- [x] Understand double quotes in builder conflict
- [x] Add changelog entry
- [x] Add integration tests
- [x] Add blog post

[dominiklohmann]

Lots of smaller comments; generally this works, but I think the default to match on individual chunks is dangerous and should be made an option instead. The default behavior of an operator should be what users want most of the time, and that isn't the case here as indicated by the warning in the documentation.

I'm approving because the required changes are really small and should not need another review. Please make them before merging, or let's postpone the blog post and discuss.