Adjust names of negated style methods (#11453)

This PR adjusts the names of the negated style methods by moving the
`neg_` to after the property name instead of before.

This will help keep related style methods grouped together in
completions.

It also makes it a bit clearer that the negation applies to the value.

### Before

```rs
div()
    .neg_mx_1()
    .neg_mt_2()
```

### After

```rs
div()
    .mx_neg_1()
    .mt_neg_2()
```

Release Notes:

- N/A

crates/collab_ui/src/chat_panel.rs

@@ -572,7 +572,7 @@ impl ChatPanel {
             )
             .child(
                 self.render_popover_buttons(&cx, message_id, can_delete_message, can_edit_message)
-                    .neg_mt_2p5(),
+                    .mt_neg_2p5(),
             )
     }
 

crates/collab_ui/src/face_pile.rs

@@ -31,7 +31,7 @@ impl RenderOnce for FacePile {
                     .into_iter()
                     .enumerate()
                     .rev()
-                    .map(|(ix, player)| div().when(ix > 0, |div| div.neg_ml_1()).child(player)),
+                    .map(|(ix, player)| div().when(ix > 0, |div| div.ml_neg_1()).child(player)),
             )
     }
 }