Pallet-examples: Add missing hooks

[ggwpez]

(Issue reserved for training purposes)

The pallet-example-basic should have all the pallet hooks as demonstration. As a start, the on_idle could be added.

[annatekl-dev]

// The on_idle hook is called when the system is idle, typically during periods when no extrinsics are being processed.

fn on_idle(n: T::BlockNumber) -> Weight {
    // Log the block number at which the on_idle hook is being called
    log::info!("on_idle called at block number {:?}", n);

    // Return weight for the operation; this indicates the computational cost
    // In this case, we return Weight::zero() because we are not performing any heavy operations
    Weight::zero()
}

[ggwpez]

Yes looks good. Please open a merge-request (if you are comfortable with this 😄).

[rainbow-promise]

Hey @annatekl-dev please signify if you still working on this. Thanks ☺️