Feature/improved signature element (#2489)

# Description

Please provide a summary of the changes, including relevant motivation
and context.

Closes #(issue_number)

## Checklist

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have performed a self-review of my own code
- [ ] I have attached images of the change if it is UI based
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [ ] My changes generate no new warnings
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

---------

Co-authored-by: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>
Co-authored-by: Reece Browne <reece@stirling.pdf>

src/main/resources/messages_en_GB.properties

@@ -831,7 +831,7 @@ sign.first=First page
 sign.last=Last page
 sign.next=Next page
 sign.previous=Previous page
-
+sign.maintainRatio=Toggle maintain aspect ratio
 #repair
 repair.title=Repair
 repair.header=Repair PDFs
@@ -1285,6 +1285,8 @@ splitByChapters.submit=Split PDF
 fileChooser.click=Click
 fileChooser.or=or
 fileChooser.dragAndDrop=Drag & Drop
+fileChooser.dragAndDropPDF=Drag & Drop PDF file
+fileChooser.dragAndDropImage=Drag & Drop Image file
 fileChooser.hoveredDragAndDrop=Drag & Drop file(s) here
 
 #release notes