For suite 'tests', parameterize the package architecture for all tests building single binary packages

This merge request parameterizes the package architecture for tests that build single binary packages in the test suite tests. It will allow meaningful experimentation with my new runner to permutate through the different architecture choices on a particular platform.

It effectively means that only architecture-dependent templates are being used. Architecture-independent packages set Package-Architecture: all.

Multiple packages will have to be split manually, if at all possible. Thank you!