XrmMock.GridControlMock Does not implement setVisible()

[improving-jeffd]

The following code mocks a grid control:
XrmMockGenerator.initialise(); XrmMockGenerator.Control.createGrid("ContactGrid", true, "Contacts");
However if the function under test is purposed to hide/show that grid the test will fail with the following error:
"Method not implemented."

This appears to be due to src/xrm-mock/controls/gridcontrol/gridcontrol.mock.ts implementing a setVisible function that just throws the error. I suppose this is probably planned for a future release... but it could also be moved to the extended ControlMock class and implemented there.