Log Message:
gopls: update to 0.5.0.

Memory usage

- Rewrite of caching model, resulting in significant memory usage improvements
  (@heschik).

New features

- Extract to function: Support for extracting code blocks that contain return
  statements (@joshbaum).
- Workspace symbols: Support for fzf-style search syntax (@findleyr). The
  following syntax is supported:
        ' for exact matching
        ^ for prefix matching
        $ for suffix matching

Note: This feature does not yet work in VS Code. See golang/vscode-go#647 and
microsoft/vscode#106788.

- An experimental new code lens to view GC optimization details (@pjweinb).
  Once the code lens is enabled, you will see a Toggle gc details annotation at
  the top of your file. Clicking it will show optimization diagnostics produced
  by the Go compiler, and clicking it once again will hide these diagnostics.
  Enable the code lens by adding the following to your settings:

     "codelens": {
     	"gc_details": true
     }

- go mod tidy and go mod vendor code lenses for go.mod files (@dandua98).
- Support for filling in matching in-scope variables instead of just empty
  values in fillstruct and fillreturns (@joshbaum).
- Autocompletion within import statements (@dandua98).
- Autocompletion within package declarations (@dandua98).

Improvements

- Improvements to workspace symbols ranking and fuzzy matching (@findleyr,
  @myitcv).
- Better completion suggestions in type switch case clauses and for calls to
  append, function literals, and unnamed types (@muirdm).