ak.argmax and ak.argmin: support for Boolean arrays

[delannoy]

Description of new feature

ak.argmax and ak.argmin do not support Boolean arrays unless they are first cast to integer. Meanwhile, np.argmax and np.argmin can operate on Boolean arrays directly:

import awkward as ak
import numpy as np

assert ak.__version__ == '2.5.1'
assert np.__version__ == '1.24.4'

np_bool_array = np.array([[1, 2, 3], [3, 2, 1]]) > 2
assert np.argmax(np_bool_array, axis=1).tolist() == [2, 0]
assert np.argmin(np_bool_array, axis=1).tolist() == [0, 1]

ak_bool_array = ak.Array([[1, 2, 3], [4, 3, 2, 1]]) > 2

try:
    ak.argmax(ak_bool_array, axis=1)
except KeyError:
    print("this doesn't work :(")

try:
    ak.argmax(np_bool_array, axis=1)
except KeyError:
    print("this doesn't work either :(")

# casting to `int` works:
ak_int_array = ak.values_astype(ak_bool_array, int)
assert ak.argmax(ak_int_array, axis=1).tolist() == [2, 0]
assert ak.argmin(ak_int_array, axis=1).tolist() == [0, 2]

[ianna]

@delannoy - thanks for brining it up! I think, we do want to be as close as possible to Numpy. Python, from version 2.3 forward, has a bool type which is a subclass of int, the standard integer type. It has two possible values: True and False, which are special versions of 1 and 0 respectively and behave as such in arithmetic contexts.

[agoose77]

Agreed with @ianna, we should support this. I'll make a PR! Thanks for the report :)