Create Dataclasses and Builder for GPU Index Build Config

[Rajrahane]

Description

Implements classes for the GPU Index Config passed to the build gpu index function
Implements a Builder and Director class for a user to initialize the config with partial params.

Issues Resolved

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[Rajrahane]

Still a WIP
Here's how you can initialize the config-

def create_index_config(**kwargs) -> GPUIndexBuildConfig:
builder = IndexConfigBuilder()
director = IndexConfigDirector(builder)
return director.construct_config(kwargs)

print(create_index_config(metric='cosinesimil', gpu_config={'graph_build_algo': 'NN_DECENT', 'ivf_pq_build_params': {'n_lists': 1040}}))