This patch enables operator presets for alembic exports.
The alembic export menu has many options, so enabling the feature will help users manage their export settings in the same way they can with other filetypes.
This solution introduces minimal changes and follows the example of how other filetypes are handled in Blender.

Code Notes:
To fix the 'Restore Operator Defaults' option, I needed to change false to true in the following line:
RNA_def_boolean(ot->srna, "init_scene_frame_range", true, "", "");