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/cmd/check.go

format-flags:
  -d,-diff
    	display diffs instead of edited file content
  -l,-list
    	display names of edited files
  -preserve
    	with -write, make copies of original files
  -w,-write
    	write edited content to source files
