format the code according to the go standard

Usage:
  gopls [flags] format [format-flags] <filerange>

The arguments supplied may be simple file names, or ranges within files.

Example: reformat this file:

	$ gopls format -w internal/lsp/cmd/check.go

format-flags:
  -d,-diff
    	display diffs instead of rewriting files
  -l,-list
    	list files whose formatting differs from gofmt's
  -w,-write
    	write result to (source) file instead of stdout
