feature request: support `provideDocumentRangeFormattingEdits` api

[bytemain]

Is your feature request related to a problem? Please describe.

setting config in vscode settings.json:

  "editor.formatOnSave": true,
  "editor.formatOnSaveMode": "modifications"

and then edit go file and save, the file will not be formatted,

Describe the solution you'd like

because when setting editor.formatOnSaveMode to modifications, VSCode will execute provideDocumentRangeFormattingEdits instead of provideDocumentFormattingEdits, currently vscode-go extension only implement provideDocumentFormattingEdits

Describe alternatives you've considered

maybe need go fmt to implement the partial format ability, if this is not planned, it is ok to close this issue.