Finish implementation of the Dash unified analytics integration with the IntelliJ stack

[jwren]

The analyzer needs to send the protocol for the new survey data, which the IntelliJ plugin now supports (see JetBrains/intellij-plugins@7295e00).

https://htmlpreview.github.io/?https://github.com/dart-lang/sdk/blob/master/pkg/analysis_server/doc/api.html - changes recorded as version 1.34.0

From Brian on some notes on how to implement:

The support is in SurveyManager (in sdk/pkg/analysis_server/lib/src/services/user_prompts/survey_manager.dart). It depends on the AnalysisServer (specifically LegacyAnalysisServer in this case) being able to return a non-null value from both userPromptSender and openUriNotificationSender. I haven't looked at LegacyAnalysisServer to see whether either of these is available.