GLSP-847 Drop dependency to sprotty-theia

[tortmayr]

Drop dependency to sprotty-theia , move dependent code in-repo and adapt existing code base.
Code that is adapted from the orginal sprotty-theia repository is proplery marked in the copyright notice and with an inline comment

Depends on: #146
Fixes eclipse-glsp/glsp#847

[martin-fleck-at]

Thank you @tortmayr for this change! The code looks mostly good to me. However, it seems that somewhere along the way something broke:

• Undo/Redo not working properly
• Copy/Paste not working properly
• The 'Diagram' menu entries in Theia are also not working as expected

They probably all have the same source because I can see the following errors in the console:
root ERROR Error: No matching bindings found for serviceIdentifier: Symbol(SelectionService)
and
Error: No matching bindings found for serviceIdentifier: EditorContextService

Maybe it is something on my end but everything builds normally, there are no additional yarn.lock changes, and the master branch works as expected. Could you please have a look at this?

[tortmayr]

Thanks for the review Martin. There was a mixup in the yarn.lock file and we ended up with two different glps-client versions....
I ran the upgrade script again and now everything seems to work.

[martin-fleck-at]

@tortmayr Yeah, that was it! Thanks for the quick update. Everything seems to work very well now. LGTM!