Add test for hywiki-mode

[matsl]

What

Add test for hywiki-mode. Also remove the :toggle argument value.

Why

Adding more line coverage and noticed a problem while doing
that. Hence a small PR that only focus on the issue.

The :toggle parameter value does not do what you would
expect. define-minor-mode does the change of the minor-mode variable
but does not recognize :toggle.

Notes

Maybe using one minor mode for three states is not the best idea after
all. Toggling twice from :pages state active leads to :all state
active.

It seems define-minor-mode and define-global-minor-mode uses a pattern
that we could benefit from.

Lets look into this again.

[rswgnu]

We need to make the three state approach work has all the latest logic I will publish depends on this.

[matsl]

We need to make the three state approach work has all the latest logic I will publish depends on this.

Yes, I understand, but the implementation might be different. Go ahead with your work we can discuss on Sunday.

Note This PR has nothing to do with the bigger pictures. It is adding a test case and removing the use of :toggle since that does not work as expected.