Improve workspace text search with notebook editors

[roblourens]

Made some improvements in #95275, this issue is to continue the work

• When doing a text search with an open notebook editor, sync find matches back into the search view, same as it works for text editors

Notes

• The SearchModel needs to listen to events for notebook editors, and bind to a notebook editor, not a text model as in normal text editors, because this is where find is implemented in notebooks.
• The SearchModel needs to be fully aware of notebook cells. Match ids need to include the match cell fragment so they don't conflict between cells

[andreamah]

Merging with #164926