Preserve sections generated by slash commands when reloading a context (#13199)

Release Notes:

- N/A

crates/assistant_slash_command/Cargo.toml

@@ -18,4 +18,5 @@ derive_more.workspace = true
 gpui.workspace = true
 language.workspace = true
 parking_lot.workspace = true
+serde.workspace = true
 workspace.workspace = true

crates/assistant_slash_command/src/assistant_slash_command.rs

@@ -1,14 +1,15 @@
 mod slash_command_registry;
 
 use anyhow::Result;
-use gpui::{AnyElement, AppContext, ElementId, Task, WeakView, WindowContext};
+use gpui::{AnyElement, AppContext, ElementId, SharedString, Task, WeakView, WindowContext};
 use language::{CodeLabel, LspAdapterDelegate};
+use serde::{Deserialize, Serialize};
 pub use slash_command_registry::*;
 use std::{
     ops::Range,
     sync::{atomic::AtomicBool, Arc},
 };
-use workspace::Workspace;
+use workspace::{ui::IconName, Workspace};
 
 pub fn init(cx: &mut AppContext) {
     SlashCommandRegistry::default_global(cx);
@@ -55,8 +56,9 @@ pub struct SlashCommandOutput {
     pub run_commands_in_text: bool,
 }
 
-#[derive(Clone)]
+#[derive(Clone, Serialize, Deserialize)]
 pub struct SlashCommandOutputSection<T> {
     pub range: Range<T>,
-    pub render_placeholder: RenderFoldPlaceholder,
+    pub icon: IconName,
+    pub label: SharedString,
 }