allow private library in one project to be referenced in another project in same workspace

This would allow projects (each of which may be linked to a different git repo) within a workspace to be able to test related changes affecting different libraries (possibly in different repos) before releasing to shared area.

Note this is not looking to have private libraries shared across workspaces, just projects within a workspace. Nor is it to “attach a private library for a shared library to a different shared library” - it makes sense that a private library is only ever bound to one shared library - but if there are multiple projects in a workspace, each using related sets of shared libraries, it would make sense to be able to use the same private library rather than binding separate private libraries to the same shared library for the same workspace.