Custom tools are ignored in project generators

[GAMMACASE]

Currently, output of custom tools like protoc, isn't included in the generated project files that's done via --gen option. Since in this particular example with protoc, the output files are placed in the build obj location and are used by the ambuild process, but are never evaluated for the project generation, which causes projects solutions to be unable to see and work with anything that depends on the generated content without manual changes.

Steps to reproduce would be to generate a VS project solution for metamod-source master and attempt to compile it within the MSVC.