Implement Text Search

[gbroques]

It's common for spreadsheets referencing a property in another document to duplicate that as a label in a nearby cell or alias in it's internal spreadsheet.

We could possibly implement this as a simple "text search" and have separate find and replace functions for "text references".

Pattern would be r'\bText\b'.

Changing an internal alias is somewhat complicated as you need to also change all references to that alias.

FreeCAD implements this by default, so maybe it's not worth addressing.

This search could be performed after a rename operation, on only the documents that were renamed.