[devtools] proper draggable for header and footer only (#80792)
Previously, the entire dialog was draggable, which conflicted with the
default user select. Therefore, only the header and the footer were
specified to be draggable, which does not include the children, e.g., a
button inside the header.
### Before
https://github.com/user-attachments/assets/c5867462-5cdd-486e-b84c-e6bbd47a4c34
### After
https://github.com/user-attachments/assets/4906898a-5442-4526-b0ce-e31ac86c1322
Closes NEXT-4547
