Problem:    Powershell core not supported by default.
Solution:   Set option defaults for "pwsh". (Mike Williams, closes #8481)

Problem:    Shell options are not set properly for PowerShell.
Solution:   Use better option defaults. (Mike Willams, closes #8459)

Problem:    Not enough testing for shell use.
Solution:   Add a bit more testing. (Yegappan Lakshmanan, closes #8469)

Problem:    Testing the shell option is incomplete and spread out.
Solution:   Move shell tests to one file and increase coverage. (Yegappan
            Lakshmanan, closes #8464)