Prompt library updates (#11988)

Restructure prompts & the prompt library.

- Prompts are now written in markdown
- The prompt manager has a picker and editable prompts
- Saving isn't wired up yet
- This also removes the "Insert active prompt" button as this concept doesn't exist anymore, and will be replaced with slash commands.

I didn't staff flag this, but if you do play around with it expect it to still be pretty rough.

Release Notes:

- N/A

---------

Co-authored-by: Nathan Sobo <1789+nathansobo@users.noreply.github.com>
Co-authored-by: Antonio Scandurra <me@as-cii.com>

crates/gpui/src/util.rs

@@ -41,6 +41,25 @@ pub trait FluentBuilder {
         })
     }
 
+    /// Conditionally unwrap and modify self with one closure if the given option is Some, or another if it is None.
+    fn when_some_else<T>(
+        self,
+        option: Option<T>,
+        then: impl FnOnce(Self, T) -> Self,
+        otherwise: impl FnOnce(Self) -> Self,
+    ) -> Self
+    where
+        Self: Sized,
+    {
+        self.map(|this| {
+            if let Some(value) = option {
+                then(this, value)
+            } else {
+                otherwise(this)
+            }
+        })
+    }
+
     /// Conditionally modify self with one closure or another
     fn when_else(
         self,

crates/gpui/src/window.rs

@@ -46,6 +46,7 @@ use std::{
 };
 use util::post_inc;
 use util::{measure, ResultExt};
+use uuid::Uuid;
 
 mod prompts;
 
@@ -4514,6 +4515,8 @@ pub enum ElementId {
     Integer(usize),
     /// A string based ID.
     Name(SharedString),
+    /// A UUID.
+    Uuid(Uuid),
     /// An ID that's equated with a focus handle.
     FocusHandle(FocusId),
     /// A combination of a name and an integer.
@@ -4528,6 +4531,7 @@ impl Display for ElementId {
             ElementId::Name(name) => write!(f, "{}", name)?,
             ElementId::FocusHandle(_) => write!(f, "FocusHandle")?,
             ElementId::NamedInteger(s, i) => write!(f, "{}-{}", s, i)?,
+            ElementId::Uuid(uuid) => write!(f, "{}", uuid)?,
         }
 
         Ok(())
@@ -4594,6 +4598,12 @@ impl From<(&'static str, u64)> for ElementId {
     }
 }
 
+impl From<Uuid> for ElementId {
+    fn from(value: Uuid) -> Self {
+        Self::Uuid(value)
+    }
+}
+
 impl From<(&'static str, u32)> for ElementId {
     fn from((name, id): (&'static str, u32)) -> Self {
         ElementId::NamedInteger(name.into(), id as usize)