The ornamental design for a cookinggrill, as shown and described.
FIG. 1 is a top, rear, perspective view of a cooking grill according to our new ornamental design;
FIG. 2 is a top view thereof;
FIG. 3 is a front view thereof; and,
FIG. 4 is a left side view thereof, with the right side view thereof being a mirror image.
The broken lines represent environment or structure and do not form any part of the claimed design.
Throughout the drawings, various views may not be provided, as the components in these views are unornamented or the ornamentation in these views is simply unclaimed.