Problem
Extensions that use CodeActionProvider to return refactorings almost always want to compute refactorings based on the current selection. The range current passed to a CodeActionProvider may be the selection or it may be the range of a diagnostic within the current document.

As a workaround, extensions have to try getting the selection from activeTextEditor

Proposal

Add a selection property to CodeActionContext. This optional property would have the current selection in the document.

Alternative designs

• Introduce a CodeActionProvider2 that has more deterministic behavior for range.
• When registering a CodeActionProvider, allow extensions to request that range should always be the current selection

/cc @kieferrm