[Feature Request] add WorkerBuilder to simplify worker usage

[bxb100]

Is your feature request related to a problem? Please describe.

Describe the solution you'd like

#[derive(Default)]
pub struct WorkerBuilder {
    core_worker: Option<Arc<dyn CoreWorker>>,
    activities: Vec<(String, BoxActFn)>,
    workflows: Vec<(String, WorkflowFunction)>,
    data: Vec<Box<dyn Send + Sync + 'static>>
}

impl WorkerBuilder {
    pub fn builder() -> Self {
        Self {
            ..Default::default()
        }
    }

    pub fn register_activity<A, R, O>(mut self, activity_type: impl Into<String>, act_function: impl IntoActivityFunc<A, R, O>) -> Self {
        self.activities.push((activity_type.into(), act_function.into_activity_fn()));
        self
    }

    pub fn register_workflow(mut self, workflow_type: impl Into<String>, wf_function: impl Into<WorkflowFunction>) -> Self {
        self.workflows.push((workflow_type.into(), wf_function.into()));
        self
    }
    
    pub fn insert_app_data<T: Send + Sync + 'static>(mut self, data: T) -> Self {
        self.datum.push(Box::new(data));
        self
    }

    pub async fn build(self) -> anyhow::Result<Worker> {
        let core_worker = self.core_worker.ok_or_else(|| anyhow!("Core worker not set"))?;
        let task_queue = core_worker.get_config().task_queue.clone();
        let mut worker = Worker::new_from_core(core_worker, task_queue);
        for (activity_type, act_func) in self.activities {
            worker.activity_half.activity_fns.insert(
                activity_type,
                ActivityFunction {
                    act_func,
                },
            );
        }
        for (workflow_type, wf_fn) in self.workflows {
            worker.register_wf(workflow_type, wf_fn);
        }
        for datum in self.data {
            worker.insert_app_data(datum);
        }
        Ok(worker)
    }
}

Additional context

[mjameswh]

@bxb100 Looks like this was meant for Core SDK, right?