Fix streaming issues

[aliabid94]

Hide status loading animation on stream, fix echo in stream on last audio chunk.

Check demo/stream_audio for example.

Still not 100% if audio streaming is being done the correct way (basically stopping and starting the MediaRecorder at 500ms intervals) but seems to work.

[abidlabs]

Just to confirm, does this close #1323, #1332, and #1494?

[freddyaboulton]

Thanks @aliabid94 !

Confirmed this fixes the audio/image streaming example. The only thing is that I noticed a very faint flicker in the audio component during flicker (you can kind of see it at second 7 in this gif) but I think that's ok

Not sure about #1323

[abidlabs]

Yup also tested this with the examples from our real time ASR guide:

from transformers import pipeline
import gradio as gr
import time

p = pipeline("automatic-speech-recognition")

def transcribe(audio, state=""):
    time.sleep(2)
    text = p(audio)["text"]
    state += text + " "
    return state, state

gr.Interface(
    fn=transcribe, 
    inputs=[
        gr.Audio(source="microphone", type="filepath", streaming=True), 
        "state"
    ],
    outputs=[
        "textbox",
        "state"
    ],
    live=True).launch()

and the examples work great! I think we can fix the flicker & clean up any other issues we fine in a future PR, but for the sake of releasing 3.1, let's go ahead and merge this in.