allow for importing benchmark functions directly from modules / package

[Hubert Baniecki]

i.e. instead of

from shapiq.games.benchmark.benchmark_config import (
    load_games_from_configuration, 
    print_benchmark_configurations
)
from shapiq.games.benchmark.plot import plot_approximation_quality

allow for

import shapiq
shapiq.games.benchmark.load_games_from_configuration()
shapiq.games.benchmark.print_benchmark_configurations()
shapiq.games.benchmark.plot_approximation_quality()

etc.