Add `streamable_http_client` which accepts `httpx.AsyncClient` instead of `httpx_client_factory` #2894

Job	Run time
checks / pre-commit	21s
checks / readme-snippets	10s
checks / test (3.10, lowest-direct, ubuntu-latest)	37s
checks / test (3.10, highest, ubuntu-latest)	39s
checks / test (3.10, highest, windows-latest)	1m 30s
checks / test (3.11, lowest-direct, ubuntu-latest)	34s
checks / test (3.12, lowest-direct, windows-latest)	1m 23s
checks / test (3.11, highest, ubuntu-latest)	34s
checks / test (3.12, lowest-direct, ubuntu-latest)	34s
checks / test (3.11, highest, windows-latest)	1m 55s
checks / test (3.12, highest, windows-latest)	1m 24s
checks / test (3.10, lowest-direct, windows-latest)	1m 19s
checks / test (3.13, highest, ubuntu-latest)	36s
checks / test (3.13, lowest-direct, ubuntu-latest)	37s
checks / test (3.12, highest, ubuntu-latest)	36s
checks / test (3.13, highest, windows-latest)	1m 34s
checks / test (3.13, lowest-direct, windows-latest)	1m 17s
checks / test (3.11, lowest-direct, windows-latest)	1m 30s
	17m 10s

Provide feedback