Expose httpx.Response streaming generators as string literals

[lu-pl]

SPARQLWrapper.query_stream and SPARQLWrapper.aquery_stream defines a streaming_method parameter that currently takes a Callable, so e.g. one can pass httpx.Response.iter_lines for line-based streaming.

This, however, requires client code to pass methods defined in httpx and therefor to define httpx as dependency (or use httpx as transient dependency, which should be avoided).

The streaming_method parameter could accept Callable | typing.Literal where Literals should denote an httpx.Response streaming method and are looked up accordingly.

[lu-pl]

Types:

from typing import Literal as TLiteral

_TStreamingMethod = TLiteral["iter_raw", "iter_bytes", "iter_text", "iter_lines"]
_TAStreamingMethod = TLiteral["aiter_raw", "aiter_bytes", "aiter_text", "aiter_lines"]

[lu-pl]

Come to think of it, the parameter for SPARQLWrapper.aquery_stream should be named astreaming_method.

Note that this would be a breaking change.