Project with PackageId containing parameter does not import nested dependencies when referenced by another project.

**Visual Studio Version**: 16.8.6

**Summary**:
When a project references another project that has a `PackageId` that contains a parameter (e.g. `MyPackage.$(SomeParameter)`), any dependencies of the referenced project are not imported into the referencing project.

**Steps to Reproduce**:

1. Create 2 projects, of which one has a `PackageId` containing a parameter and at least one `Project/PackageReference`.
2. Reference this project in the other project.

**Expected Behavior**:
The project reference tree contains both the referenced project and the references of that project (see green arrow in image below)

**Actual Behavior**:
The project reference tree doesn't contain any reference of the referenced project (see red arrow in image below)

**User Impact**:
Due to this issue, we need to include a lot of additional package/project references required by the projects references whereas this usually is taken care of by the project system.