Introduce a new /workflow command (#15854)

This subsumes the previous built-in prompt.

Release Notes:

- N/A

crates/ui/src/components/icon.rs

@@ -223,6 +223,7 @@ pub enum IconName {
     Rerun,
     Return,
     Reveal,
+    Route,
     RotateCcw,
     RotateCw,
     Save,
@@ -385,6 +386,7 @@ impl IconName {
             IconName::Reveal => "icons/reveal.svg",
             IconName::RotateCcw => "icons/rotate_ccw.svg",
             IconName::RotateCw => "icons/rotate_cw.svg",
+            IconName::Route => "icons/route.svg",
             IconName::Save => "icons/save.svg",
             IconName::Screen => "icons/desktop.svg",
             IconName::SearchSelection => "icons/search_selection.svg",