Specify and create an executionContext/pause and unpause methods

[kustosz]

Summary

We should give the IDE an option to temporarily disable automatic execution. To that end, we need to design and implement additional messages in the protocol.

Value

When building a pipeline consisting of computationally expensive steps, it is sometimes useful to postpone execution until a larger amount of work has been done. Pausing automatic execution allows to achieve that.

Specification

The pause and unpause messages should stop and resume automatic execution of execution contexts on changes. The contexts should still watch the source changes and update their internal state, but abstain from actually executing user code and sending expression value updates.

Even when paused, the visualizations system should remain unaffected (allowing the users to use visualizations for pre-computed values).

• Specify the executionContext/pause and executionContext/unpause messages in the protocol document.
• Determine how these should work internally.
• Implement these messages in the language server.
• Implement their backing functionality in the backend.

Acceptance Criteria & Test Cases

• The functionality is well documented and tested automatically.