Expose log toggability through button or checkbox

[birdzix]

Can be unintuitive to find via the context menu options

[birdzix]

In the xicam.gui.widgets.imageviewmixins module, we either create a new imageview mixin class that adds a checkable button or checkbox (see LogScaleIntensity for an example of adding a button)

Handle non-valid values (e.g. 0).

Also, this should apply to plots as well (write a plot mixin).