Summary: When traceback is present, give it 64px, or more if available, or less if less is needed. If less space is available than needed, the traceback will scroll within its allocated area.
Test Plan: The test FieldEditorSizing which tests basic sizing still passes; details with different size of formula and traceback were tested manually.
Reviewers: jarek
Reviewed By: jarek
Subscribers: jarek
Differential Revision: https://phab.getgrist.com/D3531
