Improve file handling of special characters in WebIDE

What does this MR do?

This fixes #54376 (closed) by escaping the hash characters in the Web IDE.

If a hash (#) was added to a file name it would crash the Web IDE.

What are the relevant issue numbers?

#54376 (closed)

Does this MR meet the acceptance criteria?

Since this is my first MR, I may need help in crafting it. I have put my comments in italics where I think things are at.

• Changelog entry added, if necessary after reading the guide, this didnt look necessary
• Documentation created/updated via this MR no change in functionality
• Documentation reviewed by technical writer or follow-up review issue created N/A
• Tests added for this feature/bug Should I add tests for this bug? If so I can.
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer