Provide fetch script for chardonnay build

[Mirko Brombin]

Before environment.sh it would be useful to provide a fetch.sh script which takes care of getting the wine release tarball.

Example:

./fetch.sh -r [version] (e.g. -r 6.12) 

If no release is specified, it is taken from the master branch via git.

[Mirko Brombin]

Implemented https://github.com/bottlesdevs/build-tools/blob/main/runners/vaniglia/fetch.sh