Increase size of icon buttons within the inline editor (#15051)

This PR increases the size of the the icon buttons within the inline
editors, both within the buffer and on the terminal. I also added
properties to make sure they always render as a square, as well as
tweaking the stop icon SVG, adding an alternative sparkle icon that fit
the same grid as the close (14x14) icon, and adding a bit more right
padding on the buffer's case so it doesn't collide with the scrollbar.
End result is that they have a bit of an easier target space area and
normalized sizes.

---

Release Notes:

- N/A

crates/ui/src/components/icon.rs

@@ -228,6 +228,7 @@ pub enum IconName {
     Snip,
     Space,
     Sparkle,
+    SparkleAlt,
     SparkleFilled,
     Spinner,
     Split,
@@ -378,6 +379,7 @@ impl IconName {
             IconName::Snip => "icons/snip.svg",
             IconName::Space => "icons/space.svg",
             IconName::Sparkle => "icons/sparkle.svg",
+            IconName::SparkleAlt => "icons/sparkle_alt.svg",
             IconName::SparkleFilled => "icons/sparkle_filled.svg",
             IconName::Spinner => "icons/spinner.svg",
             IconName::Split => "icons/split.svg",