UV: Move on Axis selected UVs operator

The operator moves selected UVs, using the num-pad for directional keys:

Modifiers control the units:
- UDIM / UV unit (NUMPAD KEY)
- Dynamic grid unit (CTRL + NUMPAD KEY)
- Pixel unit (SHIFT + NUMPAD KEY)

Implements design task #78405.

Ref !139608

scripts/presets/keyconfig/keymap_data/blender_default.py

@@ -1418,6 +1418,24 @@ def km_uv_editor(params):
         op_menu("IMAGE_MT_uvs_merge", {"type": 'M', "value": 'PRESS'}),
         op_menu("IMAGE_MT_uvs_split", {"type": 'M', "value": 'PRESS', "alt": True}),
         op_menu("IMAGE_MT_uvs_align", {"type": 'W', "value": 'PRESS', "shift": True}),
+        *[
+            (
+                "uv.move_on_axis",
+                {"type": key, "value": 'PRESS', **mod_dict},
+                {"properties": [("axis", axis), ("type", move_type), ("distance", distance)]}
+            )
+            for mod_dict, move_type in (
+                ({"ctrl": True}, 'DYNAMIC'),
+                ({"shift": True}, 'PIXEL'),
+                ({}, 'UDIM'),
+            )
+            for key, axis, distance in (
+                ('NUMPAD_8', 'Y', 1),
+                ('NUMPAD_2', 'Y', -1),
+                ('NUMPAD_6', 'X', 1),
+                ('NUMPAD_4', 'X', -1),
+            )
+        ],
         ("uv.stitch", {"type": 'V', "value": 'PRESS', "alt": True}, None),
         ("uv.rip_move", {"type": 'V', "value": 'PRESS'}, None),
         ("uv.pin", {"type": 'P', "value": 'PRESS'},

scripts/startup/bl_ui/space_image.py

@@ -484,6 +484,7 @@ class IMAGE_MT_uvs(Menu):
         layout.operator_context = 'EXEC_REGION_WIN'
         layout.menu("IMAGE_MT_uvs_align")
         layout.operator("uv.align_rotation")
+        layout.operator_menu_enum("uv.move_on_axis", "type", text="Move on Axis")
 
         layout.separator()