Add icon placeholders for all the armature ops that got recently added in the toolbar

The icon designers still need to create these, but it's better to have placeholders
so they remember to do it.

release/scripts/startup/bl_ui/space_toolsystem_toolbar.py

@@ -228,7 +228,7 @@ class _defs_edit_armature:
     def bone_envelope():
         return dict(
             text="Bone Envelope",
-            icon=None,
+            icon="ops.transform.bone_envelope",
             widget=None,
             keymap=(
                 ("transform.transform",
@@ -241,7 +241,7 @@ class _defs_edit_armature:
     def bone_size():
         return dict(
             text="Bone Size",
-            icon=None,
+            icon="ops.transform.bone_size",
             widget=None,
             keymap=(
                 ("transform.transform",
@@ -616,7 +616,7 @@ class _defs_pose:
     def breakdown():
         return dict(
             text="Breakdowner",
-            icon=None,
+            icon="ops.pose.breakdowner",
             widget=None,
             keymap=(
                 ("pose.breakdown", dict(), dict(type='ACTIONMOUSE', value='PRESS')),
@@ -627,7 +627,7 @@ class _defs_pose:
     def push():
         return dict(
             text="Push",
-            icon=None,
+            icon="ops.pose.push",
             widget=None,
             keymap=(
                 ("pose.push", dict(), dict(type='ACTIONMOUSE', value='PRESS')),
@@ -638,7 +638,7 @@ class _defs_pose:
     def relax():
         return dict(
             text="Relax",
-            icon=None,
+            icon="ops.pose.relax",
             widget=None,
             keymap=(
                 ("pose.relax", dict(), dict(type='ACTIONMOUSE', value='PRESS')),