Fix for undo/redo and editor toolbar actions

[oleosterhagen]

Fixes #1188 and #1211

The first commit insures that on editor part activation the toolbar buttons (e.g. Show Whitespace Characters) and global action handlers (e.g. Undo Typing) are correctly restored.

The second commit enables the buttons from the Editor Presentation toolbar (e.g. Show Whitespace Characters) for the Gradle Build Script Editor (like the Default Text Editor or Generic Editor).

[donat]

This is fantastic, thanks for providing the fix. 👀

[donat]

@oleosterhagen Thank you for the contribution!

[oleosterhagen]

Thank you very much @donat!

I think #1208 (a duplicate) and #1211 can now be closed.

[donat]

That's right, I've closed those issues. Thanks for mentioning them.