Allow to change interactive option of layer

[Falke-Design]

Makes it possible to toggle interactive options over setStyle.
New function setInteractive for ImageOverlay because it has no setStyle

Fix: #2669, #5442

[johnd0e]

There is no reliable way to change interactive option, because there may be special actions in constructor.

[Falke-Design]

@johnd0e in which constructor? Currently we don't have special actions in one of the constructors ... Only in the onAdd & onRemove and if it can added / removed, it can be toggled too.

This is a very helpful feature which makes it possible to disable all listeners on a layer without removing them.

I would like to reopen this PR and discuss about this. @mourner do you see it like @johnd0e?

[johnd0e]

in which constructor?

initialize function

Only in the onAdd & onRemove

So the option can be safely changed only when feature is not on map (in the moment of setStyle call).
Pretty useless, as for me.

[johnd0e]

Imho it is better to refactor leaflet to include common extension methods like _initInteraction(true/false), and then we can implement changing of this option in any way (preferable dedicated, not setStyle).

[Falke-Design]

@johnd0e I still think it would be useful (and working) if the interactive can changed while the layer is on the map. But it sounds like a good solution to add a general function _initInteraction(true/false) for layers. But in my eyes it would be better to make it a public function.

Btw. is it wanted that you named the function _initInteraction and not _initInteractive?

[johnd0e]

setInteractive(boolean) for public method.
And _initInteraction() for it's private part (if we need it, which is not clear yet).