Cleanup markers on close & consider marker reason

[planger]

With this change, we clean-up all markers on close of a diagram widget but only keep by default those markers that have been added by a live validation.

eclipse-glsp/glsp#980

For review, please see the comment on which changes belong together.

Change-Id: I62e515505a4a4afeed1d187393a471073d22a089

[planger]

Build failure is expected as it depends on the protocol change:

@eclipse-glsp/theia-integration: src/browser/diagram/theia-marker-manager.ts(16,72): error TS2305: Module '"@eclipse-glsp/client/lib"' has no exported member 'MarkersReason'.

[tortmayr]

Thanks Philip, support for live validation is definitely a nice feature addition.
I did not have time to test the changes yet and only did a preliminary code review for now.

[planger]

Thank you for the swift and excellent review! I've applied your suggestions in 3836bb7.

[tortmayr]

LGTM! Once the client change is merged we can update the locked version and merge this aswell.

[tortmayr]

Idea for a follow-up issue/feature:
I think it would be nice if we also would provide the option to enable/disable live validation via the Theia settings.

[planger]

I think it would be nice if we also would provide the option to enable/disable live validation via the Theia settings.

Good idea, I've tracked it here for now: eclipse-glsp/glsp#980 (comment)

@tortmayr Also, can you please re-check f4eab49 in which I've upgraded the yarn.lock? I ran yarn upgrade:next in the theia integration repo, but this resulted in quite a lot of updates, which is why I think it makes sense if you double-check.
If this is ok, feel free to directly squash and merge. Thank you!