Move "go imports search" to core workflow

Created by: ryankscott

As we move to bringing extensions to the core workflow we need to identify and migrate the most used extensions to core functionality. The "go imports search" is the most used extension (by users) and one of the most used by servers.

The extension makes it easier to search all files using a Go package by creating a new operator go.imports:() and replaces the significantly longer search query required without the operator.