Fix long line issue in partitioner client

[eric-anderson]

The default requests code can be quadratic in the data size if it finds a single long line without a newline because it is doing the standard append to a string trick. Switch over to chunking based on raw data and explicitly handle splitting by lines for the early status output.

[MarkLindblad]

Update the MockResponses in test_aryn_partitioner.py to include an iter_content

FAILED sycamore/tests/unit/transforms/test_aryn_partitioner.py::TestArynPDFPartitioner::test_partition - AttributeError: 'MockResponseNoTables' object has no attribute 'iter_content'
FAILED sycamore/tests/unit/transforms/test_aryn_partitioner.py::TestArynPDFPartitioner::test_partition_extract_table_structure - AttributeError: 'MockResponseTables' object has no attribute 'iter_content'