Make all status bar tools able to hide its button via UI (#54971)

Closes https://github.com/zed-industries/zed/discussions/53471

Adds a requirement on status bar items to provide a way to hide
themselves.

<img width="329" height="153" alt="image"
src="https://github.com/user-attachments/assets/b98ee5ba-a439-44d7-9ab5-f4511b66a574"
/>

<img width="464" height="40" alt="image"
src="https://github.com/user-attachments/assets/b41d9189-3475-4e61-b3a4-bc731dd52c53"
/>


Release Notes:

- Added a way to hide sidebar buttons

crates/encoding_selector/src/active_buffer_encoding.rs

@@ -3,13 +3,13 @@ use crate::{EncodingSelector, Toggle};
 use editor::Editor;
 use encoding_rs::{Encoding, UTF_8};
 use gpui::{
-    Context, Entity, IntoElement, ParentElement, Render, Styled, Subscription, WeakEntity, Window,
-    div,
+    App, Context, Entity, IntoElement, ParentElement, Render, Styled, Subscription, WeakEntity,
+    Window, div,
 };
 use project::Project;
 use ui::{Button, ButtonCommon, Clickable, LabelSize, Tooltip};
 use workspace::{
-    StatusBarSettings, StatusItemView, Workspace,
+    EncodingDisplayOptions, HideStatusItem, StatusBarSettings, StatusItemView, Workspace,
     item::{ItemHandle, Settings},
 };
 
@@ -131,4 +131,13 @@ impl StatusItemView for ActiveBufferEncoding {
 
         cx.notify();
     }
+
+    fn hide_setting(&self, _: &App) -> Option<HideStatusItem> {
+        Some(HideStatusItem::new(|settings| {
+            settings
+                .status_bar
+                .get_or_insert_default()
+                .active_encoding_button = Some(EncodingDisplayOptions::Disabled);
+        }))
+    }
 }