Run `v vet` and `v fmt` over most of the .v files of the V repo.

Usage:
  v test-cleancode [-fix]

The command runs v vet over `vlib/v`, `vlib/json2`, `vlib/x/ttf`,
`cmd/v`, `cmd/tools` and several examples folders, and then checks the
formatting of most of the .v files of the checkout with
`v fmt -verify`.

  -fix   instead of only reporting formatting differences, fix them by
         running `v fmt -w` over the same files.
