this should make roslyn to turn off full project diagnostics when intellisense build is failed for the project.

when we detect intellisense build failure, VS should put actionable data in error list detail pane.
also bing search for the issue should work as well if one prefer blogs.

this change also fix some issue on cross language p2p references. before there was case where we fail to connect cross language p2p reference causing a lot of errors.

this change also include bulk diagnostic update events improvement. this should let us to deal better (especially when we clean those up) when there are a lot of diagnostics.