Auto widen session incoming-window in AMQP 1.0 client

[ansd]

This commit fixes a bug in the Erlang AMQP 1.0 client.

Prior to this commit, to repro this bug:

1. Send more than 2^16 messages to a queue.
2. Grant more than a total of 2^16 link credit initially (on a single link
   or across multiple links) on a single session without any
   auto or manual link credit renewal.

The expectation is that thanks to sufficiently granted initial link-credit,
the client will receive all messages.
However, consumption stops after exactly 2^16-1 messages.

That's because the client lib was never sending a flow frame to the server.
So, after the client received all 2^16-1 messages (the initial
incoming-window set by the client), the server's remote-incoming-window
reached 0 causing the server to stop delivering messages.

The expectation is that the client lib automatically handles session
flow control without any manual involvement of the client app.

This commit implements this fix:

• We keep the server's remote-incoming window always large by default as
  explained in https://www.rabbitmq.com/blog/2024/09/02/amqp-flow-control#incoming-window
• Hence, the client lib sets its incoming-window to 100,000 initially.
• The client lib tracks its incoming-window decrementing it by 1 for
  every transfer it received. (This wasn't done prior to this commit.)
• Whenever this window shrinks below 50,000, the client sends a flow
  frame without any link information widening its incoming-window back to 100,000.
• For test cases (maybe later for apps as well), there is a new function
  amqp10_client_session:flow/3, which allows for a test case to do manual
  session flow control. Its API is designed very similar to
  amqp10_client_session:flow_link/4 in that the test can optionally request
  the lib to auto widen the session window whenever it falls below a certain threshold.