Provide a mechanism to replace the "Plugins Callbacks"

[vivien-apple]

Problem

With #3464 all Plugins Callbacks are gone. But as it can be seen in #3782 some of them are already used in examples/.

While #3782 does not changed the behavior of the app with the current shape of the thee, it may introduce some issues once CHIP will support tokens or attributes initialisation to a specific value.

A mechanism equivalent to Plugins Callbacks needs to be introduced in CHIP in order to allow the use case of #3782

More generally, the provided mechanism should works across clusters to provide a global mechanism since the Plugins callbacks are likely fitting use cases from the field.

Proposed Solution

Implement a mechanism similar to Plugins Callbacks. It could be based on CHIPCallback.

One of the main difference with what was previously done with AppBuilder is that one could consider CHIP to have those "plugins" by default. AppBuilder uses to generate callbacks stubs and provide the method declarations from the gen/ folder. But in our case the "plugins" are permanent and it can be done differently.

[woody-apple]

SW Dev Bug Review: Closing this, as doesn't appear needed anymore and/or is complete, please reopen if needed.