fix go work syntax having wrong highlighting entirely

[ArtAndreev]

go.work file has wrong syntax highlighting:

The reason is broken regexp that colors all file wrong:

syntax match goworkPath "\f\+"

I suggest to drop this regexp, because path can be treated like module name without version, and provide the same highligthing for use block as for require block in go.mod:

Also I did some housekeeping in file.

PR with the same changes is opened in vim-polyglot: sheerun/vim-polyglot#819.

[bhcleek]

Thank you