Add ability to copy a package definition in NI Package Builder

[MaximeR]

Inside NI Package Builder, you can define different packages for a solution.

Because you have a lot of option to configure and many are more just for information, it can be easier to be able to copy an already existing package than start from 0 for each package.

I don't think it cost a lot because .pbs are XML based. I don't want to build my one tool and modify the xml to be able to do that.