[WIP]Yield with uploads

[ElijahAhianyo]

This PR should have uploads working with yield. The code below should work:

import reflex as rx


class State(rx.State):
    img : list[str] = []
    val : str = "new"

    async def handle_upload(self, files : list[rx.UploadFile]):
        for file in files:
            upload_data = await file.read()
            outfile = f".web/public/{file.filename}"

            # Save the file.
            with open(outfile, "wb") as file_object:
                file_object.write(upload_data)

            # Update the img var.
            self.img.append(file.filename)

        yield State.set_value("Finished uploading")

    def set_value(self, val: str):
        self.val = val

    def upload_and_update(self, files : list[rx.UploadFile] ):

        yield State.set_value("uploading value")
        yield State.handle_upload(files)


def index():
    return rx.center(
        rx.vstack(
            rx.text(State.val),
            rx.upload(
                rx.button("Select File"),
                rx.text("Drag and drop files here or click to select files"),
                border="1px dotted black",
                padding="20em",
            ),
            rx.button(
                "Upload",
                on_click=lambda: State.handle_upload(rx.upload_files())
            ),
            rx.foreach(State.img, lambda img: rx.image(src=img)),
        )
    )


app = rx.App(state=State)
app.add_page(index)
app.compile()