Improve strategy of finding correct default package to build.

[User344]

Current strategy is to look at "default-members" of workspace section in Cargo.toml and search packages that have "bin" target in them.

The problems with this approach are next:

• We only support building one package per action, so if there are multiple packages matching above criteria there is no way to know which one should be used. Should support for building multiple packages be added in this case?
• We only look for "bin" targets, but "dylib", "cdylib" and other crate types also produce artifacts. Do we look for every crate type that produces artifacts when looking for potential package? It might make first problem even more visible.