Testing framework provided by stdlib

[awvwgk]

Should stdlib provide a testing framework on it own, which is available to downstream users?

Related discussions

• error object: Error stack class/object #95
• assertions: Implement standard assert subroutine and associated macros #72
• testing framework for stdlib: Proposal to use Testing Framework #162

[awvwgk]

Closing in favor of developing the test-drive project maintained in @fortran-lang namespace.