Deprecate top level quantization APIs (#344)

[jerryzh168]

Summary:
This PR deprecates a few quantization APIs and here are the bc-breaking notes:

1. int8 weight only quantization int8 weight only quant module swap API

apply_weight_only_int8_quant(model)

and
int8 weight only tensor subclass API

change_linear_weights_to_int8_woqtensors(model)

-->

unified tensor subclass API

quantize(model, get_apply_int8wo_quant()))

2. int8 dynamic quantization

apply_dynamic_quant(model)

or

change_linear_weights_to_int8_dqtensors(model)

-->

unified tensor subclass API

quantize(model, get_apply_int8dyn_quant()))

3. int4 weight only quantization

change_linear_weights_to_int4_wotensors(model)

-->

unified tensor subclass API

quantize(model, get_apply_int4wo_quant()))

Test Plan:
python test/quantization/test_quant_api.py
python test/integration/test_integration.py

Reviewers:

Subscribers:

Tasks:

Tags:

[pytorch-bot]

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[jerryzh168]

looks like there are not many tests for the release branch cherry-pick merge