Move IDEOverlays into a separate component

[lindapaiste]

Progress on #1458

Merge after #2335

Changes:

• Move the section of the code for rendering modals and overlays out of IDEView and into a new component IDEOverlays, as discussed in Refactor IDEView #1458

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #123

[raclim]

Thanks so much for working on this!

As we discussed earlier, updating the snapshots here might not have been the best solution, but I felt that we could create a separate issue about it if needed!