Ability to automatically launch MSI installer after creating it

[filips123]

Currently, running cargo wix just builds the project and creates an MSI file, but the user still needs to manually launch it. Although this is fine in most cases (the project will probably be built somewhere else and the user will just get the MSI file), it would still be useful to have an option to automatically launch the MSI file just after creating it.

For example, this would be useful to provide users a way to easily build and install the project from the source (you just need to tell them to run cargo wix --install or something, so they don't need to manually search for the file) or for usage in scripts (as it would be easier to just specify --install instead of manually checking which MSI file is correct, in case there are still existing files from previous versions, and launching it).

cargo-deb has such option cargo deb --install to automatically install the created DEB file.