Let LineColumn on StatusBar as clickable to open GoToLineColumn (#9002)

Release Notes:

- Added to let LineColumn on StatusBar as clickable to open
GoToLineColumn.
- Added placeholder to GoToLineColumn input, and show help message on
input changed.

## Screenshot


![go-to-line-column](https://github.com/zed-industries/zed/assets/5518/90a4f644-07d4-4208-8caa-5510e1537f37)

crates/editor/src/items.rs

@@ -7,9 +7,9 @@ use anyhow::{anyhow, Context as _, Result};
 use collections::HashSet;
 use futures::future::try_join_all;
 use gpui::{
-    div, point, AnyElement, AppContext, AsyncWindowContext, Context, Entity, EntityId,
-    EventEmitter, IntoElement, Model, ParentElement, Pixels, Render, SharedString, Styled,
-    Subscription, Task, View, ViewContext, VisualContext, WeakView, WindowContext,
+    point, AnyElement, AppContext, AsyncWindowContext, Context, Entity, EntityId, EventEmitter,
+    IntoElement, Model, ParentElement, Pixels, SharedString, Styled, Task, View, ViewContext,
+    VisualContext, WeakView, WindowContext,
 };
 use language::{
     proto::serialize_anchor as serialize_text_anchor, Bias, Buffer, CharKind, OffsetRangeExt,
@@ -21,7 +21,6 @@ use rpc::proto::{self, update_view, PeerId};
 use settings::Settings;
 use workspace::item::ItemSettings;
 
-use std::fmt::Write;
 use std::{
     borrow::Cow,
     cmp::{self, Ordering},
@@ -33,11 +32,8 @@ use std::{
 use text::{BufferId, Selection};
 use theme::Theme;
 use ui::{h_flex, prelude::*, Label};
-use util::{paths::PathExt, paths::FILE_ROW_COLUMN_DELIMITER, ResultExt, TryFutureExt};
-use workspace::{
-    item::{BreadcrumbText, FollowEvent, FollowableItemHandle},
-    StatusItemView,
-};
+use util::{paths::PathExt, ResultExt, TryFutureExt};
+use workspace::item::{BreadcrumbText, FollowEvent, FollowableItemHandle};
 use workspace::{
     item::{FollowableItem, Item, ItemEvent, ItemHandle, ProjectItem},
     searchable::{Direction, SearchEvent, SearchableItem, SearchableItemHandle},
@@ -1199,83 +1195,6 @@ pub fn active_match_index(
     }
 }
 
-pub struct CursorPosition {
-    position: Option<Point>,
-    selected_count: usize,
-    _observe_active_editor: Option<Subscription>,
-}
-
-impl Default for CursorPosition {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-impl CursorPosition {
-    pub fn new() -> Self {
-        Self {
-            position: None,
-            selected_count: 0,
-            _observe_active_editor: None,
-        }
-    }
-
-    fn update_position(&mut self, editor: View<Editor>, cx: &mut ViewContext<Self>) {
-        let editor = editor.read(cx);
-        let buffer = editor.buffer().read(cx).snapshot(cx);
-
-        self.selected_count = 0;
-        let mut last_selection: Option<Selection<usize>> = None;
-        for selection in editor.selections.all::<usize>(cx) {
-            self.selected_count += selection.end - selection.start;
-            if last_selection
-                .as_ref()
-                .map_or(true, |last_selection| selection.id > last_selection.id)
-            {
-                last_selection = Some(selection);
-            }
-        }
-        self.position = last_selection.map(|s| s.head().to_point(&buffer));
-
-        cx.notify();
-    }
-}
-
-impl Render for CursorPosition {
-    fn render(&mut self, _: &mut ViewContext<Self>) -> impl IntoElement {
-        div().when_some(self.position, |el, position| {
-            let mut text = format!(
-                "{}{FILE_ROW_COLUMN_DELIMITER}{}",
-                position.row + 1,
-                position.column + 1
-            );
-            if self.selected_count > 0 {
-                write!(text, " ({} selected)", self.selected_count).unwrap();
-            }
-
-            el.child(Label::new(text).size(LabelSize::Small))
-        })
-    }
-}
-
-impl StatusItemView for CursorPosition {
-    fn set_active_pane_item(
-        &mut self,
-        active_pane_item: Option<&dyn ItemHandle>,
-        cx: &mut ViewContext<Self>,
-    ) {
-        if let Some(editor) = active_pane_item.and_then(|item| item.act_as::<Editor>(cx)) {
-            self._observe_active_editor = Some(cx.observe(&editor, Self::update_position));
-            self.update_position(editor, cx);
-        } else {
-            self.position = None;
-            self._observe_active_editor = None;
-        }
-
-        cx.notify();
-    }
-}
-
 fn path_for_buffer<'a>(
     buffer: &Model<MultiBuffer>,
     height: usize,