Added function to tree widget to find a node by the data field

[BurnoutDV]

Based on the monologue discussion #5315

I added a function to the Tree Widget for finding a node based on the supplied data field. Its probably inefficient but I couldn't think of a better way to achieve what I wanted with arbitrary json data. There is also the case that there might be a list instead of a dictionary where one might want to find a node that matches any one value.

I could extend the functionality to find all matching nodes and make it match any one value in a list or nested list if there is interest for the basic idea.

Maybe finding notes based on supplied data is to much of a deviation from the base implementation.

Please review the following checklist.

• [ X] Docstrings on all new or modified functions / classes
• [ ] Updated documentation
• [ ] Updated CHANGELOG.md (where appropriate)