docs: clarify listener close with pending accept (#34612)

Document that callers should wait for pending Deno.Listener.accept
operations to settle after closing a listener before immediately
listening on the same address again.

Add regression coverage for both an explicit accept promise and the
async iterator next() path before re-listening on the same port.

Verification:
- git diff --check
- cargo check -p deno_net
- cargo test -p unit_tests --test unit -- net_test (blocked: local
target/debug/deno was missing, and building it failed because the
filesystem ran out of space)

Closes denoland/orchid#367

Co-authored-by: divybot <divybot@users.noreply.github.com>
Co-authored-by: Divy Srivastava <me@littledivy.com>