Add LSP call hierarchy modal (#53239)

<img width="1128" height="953" alt="image"
src="https://github.com/user-attachments/assets/b2017c0a-e25a-49d7-9342-d074014d085c"
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Closes #14203

Release Notes:
- Initial Call Hierarchy support in Zed

---------

Co-authored-by: Alexey Olshanskiy <gh@aohoy.dev>
Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Kirill Bulatov <kirill@zed.dev>

docs/src/finding-navigating.md

@@ -42,6 +42,15 @@ Jump to where a symbol is defined with {#kb editor::GoToDefinition} (or `Cmd+Cli
 - **Current file:** {#kb outline::Toggle} opens an outline of symbols in the active file
 - **Entire project:** {#kb project_symbols::Toggle} searches symbols across all files
 
+## Call Hierarchy
+
+With the cursor on a function, {#action call_hierarchy::ShowIncomingCalls} ({#kb call_hierarchy::ShowIncomingCalls}) lists the functions that call it, and {#action call_hierarchy::ShowOutgoingCalls} lists the functions it calls.
+Both open a picker; selecting an entry jumps to the call site, and the secondary confirm opens it in an adjacent pane.
+While the picker is open, {#action call_hierarchy::ToggleDirection} switches between callers and callees, {#action menu::SelectChild} re-roots the hierarchy at the selected function to explore one level deeper, and {#action menu::SelectParent} steps back up; the picker's footer shows the corresponding key bindings.
+Both actions are also available in the editor's right-click menu.
+The modal's width can be changed via the `call_hierarchy.modal_max_width` setting.
+This requires the language server to support call hierarchy.
+
 ## Outline Panel
 
 The Outline Panel ({#kb outline_panel::ToggleFocus}) shows a persistent tree view of symbols in the current file. It's especially useful with [multibuffers](./multibuffers.md) for navigating search results or diagnostics.

docs/src/reference/all-settings.md

@@ -3570,6 +3570,14 @@ Examples:
 
 `boolean` values
 
+## Call Hierarchy
+
+### Modal Max Width
+
+- Description: Max-width of the call hierarchy modal. It can take one of these values: `small`, `medium`, `large`, `xlarge`, and `full`.
+- Setting: `modal_max_width`
+- Default: `medium`
+
 ## File Finder
 
 ### File Icons