puffin_http clients can't get firsts frame if they are short

[gwen-lg]

Describe the bug
When firsts frames are short, puffin_http client (example: puffin_viewer) can't get firsts frames.

To Reproduce
Steps to reproduce the behavior:

1. start puffin_viewer
2. start an app with puffin_http server with short frames (and numbered frames)
3. look-at frame in viewer, there isn't the first frame(s)

Expected behavior
I expect to be able to get first frame in puffin_viewer

Device:

• OS: Fedora
• Version 36

[gwen-lg]

I have look at the code of server_http, and see than the call to accept_new_clients depend of frame present in channel.
It could be good to allow client registering to be independent of frame available.

One solution could be to move connection with client cloud be done in another thread ?
Or be able to wait on both frames channel and tcp_listener in same time (with async ?)

PS: I'm interested to working on it, but opinions are welcome before I tried to implement a fixe