Copying nodes:
- Multiple nodes supported.
- Node comments and user-specified colors included.
- Google Sheets data can be pasted to produce a `Table` node, handled the same way as Excel data.
# Important Notes
- Fix E2E tests on OS X.
- Add E2E and unit tests for clipboard.
- Use the lexer to test text escaping; fix text escaping issues and inconsistencies.
Fixes#6250
With this change, I've also slightly refactored the graph editor component by grouping related functionality into neat block and moving already loosely coupled groups to separate files. Further work will be needed to simplify it, but it is a good first step.
https://github.com/enso-org/enso/assets/919491/fedce111-ea79-463f-a543-da3ecce28bf5
Fixes#9314
The node deletion does not remove AST node from the module, only unpin it from its parent; so undoing does not add this node, just modify it, and thus we weren't informed about metadata change.
