add ChunkKV

[Dominic789654]

PR Description

Add ChunkKV paper implementation (https://arxiv.org/abs/2502.00299)

Benchmark Results

Results on Ruler (4096) dataset under different compression ratios (0.1, 0.25, 0.5):

Task	0.1	0.25	0.5
cwe	99.66	99.48	97.14
fwe	94.47	94.33	93.53
niah_multikey_1	99.0	95.4	82.4
niah_multikey_2	86.8	65.6	41.8
niah_multikey_3	86.8	60.4	27.4
niah_multiquery	98.85	93.55	76.85
niah_multivalue	98.15	91.05	77.6
niah_single_1	100.0	100.0	100.0
niah_single_2	99.2	97.6	90.0
niah_single_3	89.6	71.8	51.8
qa_1	87.8	86.0	82.6
qa_2	61.0	60.4	76.85
vt	99.88	99.88	77.6
Average	92.40	85.81	75.04

New press checklist

• I added mypress_press.py in the presses directory
• I added MyPress in __init__.py
• I updated the README.md with a 1 liner about my new press in the Available presses section
• I added my press in the default_presses list in tests/default_presses.py

[maxjeblick]

Thanks a lot for opening this PR!
The overall code looks good, thanks for adding it. There are several points that I'd ask to address before merging:

• We prefer to have a new press class (ChunkKVPress) associated with your paper, as your method (selecting whole chunks) differs from ChunkPress's idea (compress each chunk independently). Both methods also have different default parameters (e.g. chunk_length).
• After introducing a new class, you can add a new test (similar to test_chunk_press). Please do not modify the existing test that uses ExpectedAttentionPress.
• Please add your class in the corresponding README section (available presses).
• Most style errors can be fixed my running make format. You can test style locally by make style. Feel free to add # noqa: flags if necessary; e.g. sometimes mypy has issues to resolve tensor attributes correctly.
• Please don't forget to sign off your commit. See https://github.com/NVIDIA/kvpress/blob/main/CONTRIBUTING.md for additional information.

Feel free to reach out with any questions or comments!