fix: HTTP/2 sends now wait up to 5 seconds for flow-control credit instead of returning send_buffer_full

[speeddragon]

Disclaimer: This PR code was generated by AI.

I'm trying to address #895. I'm having the same issue with ex_aws, and this PR modifies the request to wait until a specific time rather than returning {error, send_buffer_full}.

This change allows waiting for the buffer to clear instead of returning an error.

How to use it with ExAws:

  config :ex_aws, :hackney_opts,
    h2_send_timeout: 5_000

Or per request:

  ExAws.request(operation, http_opts: [h2_send_timeout: 10_000]) 

TODO

• Run rebar3 eunit
• Update documentation about the new property

[benoitc]

It seems that what you want is blocking send i but is there any reason you need a configurable send wait per request ? I don't see a real use case for h2_send_timeoutand the complexity it adds.

This will change the behabiour though, instead of returnong once the 1MB buffer cap is crossed {error, send_buffer_full} , the application will have to wait for a {error, timeout}