add missing execution space in mdrange

[yasahi-hpc]

This PR aims at fixing bugs about execution space in MDRange in some internal helpers.
For example, following modifications are made

// Previous, exec_space was missing
range_type range(
    point_type{{0, 0}}, point_type{{len0, len1}}, tile_type{{4, 4}}
    // [TO DO] Choose optimal tile sizes for each device
 );

// After fix
range_type range(
    exec_space, point_type{{0, 0}}, point_type{{len0, len1}},
    tile_type{{4, 4}}  // [TO DO] Choose optimal tile sizes for each device
);

[cedricchevalier19]

Good catch.

Arg name deletion can be done as another PR.

[yasahi-hpc]

Good catch.

Arg name deletion can be done as another PR.

Thank you for your review. I have modified accordingly.
Arg name deletion may be done in your PR?