Support for Calling Device Functions from numba.jit functions

[PokhodenkoSA]

DPPY device functions can not be called from @numba.jit functions.

Example:
Example:

@dppy.func
def a_device_function(a):
    return a + 1

@numba.jit(nopython=True)
def a_numba_function(x):
    return a_device_function(x)

def test_device_function():
    context = get_context()
    with dpctl.device_context(context):
        C = a_numba_function(10)

    print(C)

Output:

numba.core.errors.TypingError: Failed in dppy_nopython mode pipeline (step: nopython frontend)
Untyped global name 'a_device_function': cannot determine Numba type of <class 'numba_dppy.compiler.DPPYFunctionTemplate'>

File "numba_dppy/examples/dppy_func.py", line 13:
def a_numba_function(x):
    return a_device_function(x)
    ^

[diptorupd]

As the name suggests, a device function cannot be called directly from host space.