Removed not-used IDE modules

What does this MR do and why?

For the whole time since we have switched WebIDE to Source Editor, the original implementation has been laying around even though it has not been used. The original point was to keep it around in case the SE-driven implementation fails. However, we didn't have a need to switch to the old implementation for more than a year. So, I think it's time for the removal 🎉

Screenshots or screen recordings

Before	After
cell	cell
cell	cell

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