The ornamental design for a badgeholder, as shown and described.
FIG. 1 is a top, front, and left side perspective view of a badge holder showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a left side elevational view thereof; and,
FIG. 4 is a right side elevational view thereof.
The back surface of the design, which is not shown in the drawings, forms no part of the claimed design.
The clip at the back of the design and the components at the bottom of the design, all depicted in broken lines, represent environmental structure that forms no part of the claimed design.