Resolve "Improve Web IDE launch performance"

What does this MR do?

Improves the performance and perceived performance of the Web IDE launch. It does this by:

• Improving the decorate_files procedure and removing the unnecessary web worker.
• Deferring a commit that triggers the rendering of the file tree. This allows the selected file to load concurrently.

Screenshots

Notice how the "After" has the file loading before hand. For non-deterministic reasons the speed difference isn't too noticeable in these two examples 😅

Before	After

What are the relevant issue numbers?

Closes #53336 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• 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