Support return int rather than always Optional in dct.get(key, default)

[dlee992]

A hacky/flaky way to
fix #9473

This test case can pass:

import numpy as np
from numba import njit
from numba.core import types
from numba.typed import Dict

@njit
def goo(arr):
    d = Dict.empty(types.int64, value_type=types.int64)
    d[0] = 0
    v1 = d.get(0, 0)
    arr[v1] = -1
    v2 = d.get(2, 9)
    arr[v2] = -2
    v3 = d.get(3)
    return arr, v3

arr = np.arange(10)
print(goo(arr))

[sklam]

We are assuming this PR is still in progress since it does not have a test yet.

[dlee992]

Hi, test is added @sklam