1552377 - Allow use of lambdas with Preference's callbacks

Status: NEW

(Core :: Preferences: Backend, task, P5)

Description

[Jean-Yves Avenard [:jya]]

To achieve this, we could modify modify CallbackNode class. It would become the base class for classes like CallbackNodeCFunc, CallbackNodeStdFunction, and maybe CallbackNodeLambda<F>

It could potentially even save heap space as there are many cases we do not need the void* aData currently always stored (though we would gain a vtable).
Other members of the current CallBackNode could potentially be removed too saving even more space.

It would then allow to do things like:

Preferences::RegisterCallback([prefName](const T& aNewValue) { ... });