Add `streamable_http_client` which accepts `httpx.AsyncClient` instead of `httpx_client_factory` #3231

Job	Run time
checks / pre-commit	37s
checks / readme-snippets	13s
checks / test (3.10, highest, ubuntu-latest)	36s
checks / test (3.10, lowest-direct, ubuntu-latest)	38s
checks / test (3.10, lowest-direct, windows-latest)	1m 20s
checks / test (3.11, lowest-direct, ubuntu-latest)	39s
checks / test (3.12, lowest-direct, windows-latest)	1m 36s
checks / test (3.11, highest, ubuntu-latest)	34s
checks / test (3.12, lowest-direct, ubuntu-latest)	36s
checks / test (3.10, highest, windows-latest)	1m 23s
checks / test (3.11, lowest-direct, windows-latest)	1m 43s
checks / test (3.12, highest, windows-latest)	1m 43s
checks / test (3.11, highest, windows-latest)	1m 34s
checks / test (3.13, lowest-direct, ubuntu-latest)	35s
checks / test (3.13, lowest-direct, windows-latest)	1m 42s
checks / test (3.13, highest, windows-latest)	1m 18s
checks / test (3.13, highest, ubuntu-latest)	37s
checks / test (3.12, highest, ubuntu-latest)	36s
	18m 0s

Provide feedback