Call ID Insertion and Resolution For #520

[tbraun96]

Resolves #520
Resolves #534

1. Define the context. TangleClientContext now requires a call_id field:

#[derive(Clone, TangleClientContext)]
pub struct MyContext {
    #[config]
    sdk_config: StdGadgetConfiguration,
    #[call_id]
    call_id: Option<u64>,
}

2. Access the call id at runtime via the context:

#[job(
    id = 0,
    params(x),
    event_listener(
        listener = TangleEventListener<MyContext, JobCalled>,
        pre_processor = services_pre_processor,
        post_processor = services_post_processor,
    ),
)]
/// Returns x^2 saturating to [`u64::MAX`] if overflow occurs.
pub fn xsquare(x: u64, context: MyContext) -> Result<u64, gadget_sdk::Error> {
    assert!(context.call_id.is_some()); // <----- Assertion success; runtime injection occurs
    Ok(x.saturating_pow(2))
}

NOTE: This only propagates the call_id from the pre-processor to the job function. The propagation from the job function to the post-processor is not covered.