[BUG] library symbols set by SDK are only used for validation

[mattmasson]

Expected behavior
We added a way for the SDK to set symbols for the current connector project. However, they don't seem to work with Hover, Signature Help, or Completion Items.

Actual behavior
The connector symbols only work with Validation operations.

To Reproduce
Create an SDK project.
Build your connector.
Open your connector.query.pq file.

[mattmasson]

This functionality seems to be broken entirely in the latest versions of both extensions.

[mattmasson]

#206 suggests an alternative mechanism for the SDK to provide connector symbols to the language service extension.