bndrun: refresh model before Resolve to get changes of included .bndrun files

[chrisrueger]

this fixes the problem that the Resolve button did not "see" changes of included .bndrun files (e.g. -include: shared.bndrun). So when you changed something in an include and pressed the "Resolve" button , then the "Resolve" process would still see the old state when the BndEditor was initially opened and as if the change to -include: shared.bndrun would not have happened. Previous workaround was to close and open the BndEditor of the actual .bndrun file again

Steps to reproduce

(you can also use this workspace3.zip)

1. Create a.bndrun

-include: shared.bndrun

2. Create a shared.bndrun

-runrequires: \
	bnd.identity;id='bar.impl',\
	bnd.identity;id='bar.consumer',\
	bnd.identity;id='org.apache.felix.gogo.command',\
	bnd.identity;id='org.apache.felix.gogo.runtime',\
	bnd.identity;id='org.apache.felix.gogo.shell'

-runfw: org.apache.felix.framework

-runrepos: \
	Workspace,\
	OSGI R8 - Build,\
	OSGI R8 - Runtime Distro

3. Now open a.bndrun and press Resolve and do not close the editor.

Resolve should Succeed.

4. Now open shared.bndrun and remove e.g. two runrepos
   -OSGI R8 - Build,
   -OSGI R8 - Runtime Distro

5. go back to the still opened a.bndrun editor and press Resolve again.

Actual Result: It still resolves sucessfully.
Expected Result: Resolve should fail, because we removed the runrepos

If you close and reopen a.bndrun and resolve again, then this will expectedly fail, because the model is reloaded and the change to 'shared.bndrun' is seen.

This PR basically does that automatically on each press to "Resolve", so that the workaround is no longer needed.

It drastically improves developer experience, because I often was misled by the previous behavior, because I made a change and was suprised that it was not used. I found out by accident that I had to reopen the editor.

[chrisrueger]

@pkriens I merged and will test it in the wild. I will keep an eye on it and revert if things broke. But it will be very useful for my other PR for the Eclipse P2 repo stuff like #6535 and #6536 where I need to update .bndrun and included .bndrun files all the time.