Remove base64 encoding from file upload in the WebIDE

What does this MR do?

This merge request fixes the issue where files were base64 encoded after uploading non-text files from the WebIDE.

When a non-text file is uploaded from the WebIDE, the file was base64 encoded and as a result, the contents of the file in the repo was base64 encoded. This MR prevents this issue by removing the base64 encoding before passing the file to the backend.

What are the relevant issue numbers?

Closes: #48746 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines

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