Add action to append project to current workspace

[ygdkn]

Hi, I think about feature to enhance GPM to work with multi-root workspace and add apility to append project to current workspace, similar to code -a

[felipecaputo]

Hi @s-yagodkin I didn't make any change yet to support multi-root workspace

I'll try to take a look at this in the weekend and let you know o/