RFE: io.Seeker Seek whence values

Would be nice to flag uses of the `Seek` method of anything that implements [`io.Seeker`](https://pkg.go.dev/io#Seeker) (for example [`os.File`](https://pkg.go.dev/os#File.Seek)) and uses magic numbers as `whence` values, and ask to replace with [`io.Seek*`](https://pkg.go.dev/io#pkg-constants) constants.