Added custom script execution operator

ExecutePreset from the following file

https://developer.blender.org/diffusion/B/browse/master/release/scripts/startup/bl_operators/presets.py;68ef6797b2fc2d2e37f59f6aae0d57b4ce8cc4bc$183

is tied into the following

https://developer.blender.org/diffusion/B/browse/master/release/scripts/modules/bpy_types.py;4ce7d5cb79e23c4b28b1f1afe11fa066f3a5ea9c$742