Add support for excluding files based on .gitignore (#26636)

Closes: #17543

Release Notes:

- **New Feature:** Introduced the ability to automatically remove files
and directories from the Zed project panel that are specified in
`.gitignore`.
- **Configuration Option:** This behavior can be controlled via the new
`project_panel.hide_gitignore` setting. By setting it to `true`, files
listed in `.gitignore` will be excluded from the project panel.
- **Toggle:** Ability to toggle this setting using the action
`ProjectPanel::ToggleHideGitIgnore`

```json
  "project_panel": {
    "hide_gitignore": true
  },

```

This results in a cleaner and easier to browse project panel for
projects that generate a lot of object files like `xv6-riscv` or `linux`
without needing to tweak `file_scan_exclusions` on `settings.json`

**Preview:**
- With `"project_panel.hide_gitignore": false` (default, this is how zed
currently looks)

![Screenshot From 2025-03-23
12-50-17](https://github.com/user-attachments/assets/15607e73-a474-4188-982a-eed4e0551061)

- With `"project_panel.hide_gitignore": true` 

![Screenshot From 2025-03-23
12-50-27](https://github.com/user-attachments/assets/3e281f92-294c-4133-b5e3-25e17f15bd4d)

- Action `ProjectPanel::ToggleHideGitIgnore`

![Screenshot From 2025-03-23
12-50-55](https://github.com/user-attachments/assets/4d03db33-75ad-471c-814c-098698a8cb38)

crates/project_panel/src/project_panel.rs

@@ -36,7 +36,7 @@ use project_panel_settings::{
 };
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
-use settings::{Settings, SettingsStore};
+use settings::{update_settings_file, Settings, SettingsStore};
 use smallvec::SmallVec;
 use std::any::TypeId;
 use std::{
@@ -197,6 +197,7 @@ actions!(
         Open,
         OpenPermanent,
         ToggleFocus,
+        ToggleHideGitIgnore,
         NewSearchInDirectory,
         UnfoldDirectory,
         FoldDirectory,
@@ -233,6 +234,13 @@ pub fn init(cx: &mut App) {
         workspace.register_action(|workspace, _: &ToggleFocus, window, cx| {
             workspace.toggle_panel_focus::<ProjectPanel>(window, cx);
         });
+
+        workspace.register_action(|workspace, _: &ToggleHideGitIgnore, _, cx| {
+            let fs = workspace.app_state().fs.clone();
+            update_settings_file::<ProjectPanelSettings>(fs, cx, move |setting, _| {
+                setting.hide_gitignore = Some(!setting.hide_gitignore.unwrap_or(false));
+            })
+        });
     })
     .detach();
 }
@@ -414,6 +422,9 @@ impl ProjectPanel {
             cx.observe_global::<SettingsStore>(move |this, cx| {
                 let new_settings = *ProjectPanelSettings::get_global(cx);
                 if project_panel_settings != new_settings {
+                    if project_panel_settings.hide_gitignore != new_settings.hide_gitignore {
+                        this.update_visible_entries(None, cx);
+                    }
                     project_panel_settings = new_settings;
                     this.update_diagnostics(cx);
                     cx.notify();
@@ -1536,7 +1547,6 @@ impl ProjectPanel {
         if sanitized_entries.is_empty() {
             return None;
         }
-
         let project = self.project.read(cx);
         let (worktree_id, worktree) = sanitized_entries
             .iter()
@@ -1568,13 +1578,14 @@ impl ProjectPanel {
 
         // Remove all siblings that are being deleted except the last marked entry
         let snapshot = worktree.snapshot();
+        let hide_gitignore = ProjectPanelSettings::get_global(cx).hide_gitignore;
         let mut siblings: Vec<_> = ChildEntriesGitIter::new(&snapshot, parent_path)
             .filter(|sibling| {
-                sibling.id == latest_entry.id
-                    || !marked_entries_in_worktree.contains(&&SelectedEntry {
+                (sibling.id == latest_entry.id)
+                    || (!marked_entries_in_worktree.contains(&&SelectedEntry {
                         worktree_id,
                         entry_id: sibling.id,
-                    })
+                    }) && (!hide_gitignore || !sibling.is_ignored))
             })
             .map(|entry| entry.to_owned())
             .collect();
@@ -2590,7 +2601,9 @@ impl ProjectPanel {
         new_selected_entry: Option<(WorktreeId, ProjectEntryId)>,
         cx: &mut Context<Self>,
     ) {
-        let auto_collapse_dirs = ProjectPanelSettings::get_global(cx).auto_fold_dirs;
+        let settings = ProjectPanelSettings::get_global(cx);
+        let auto_collapse_dirs = settings.auto_fold_dirs;
+        let hide_gitignore = settings.hide_gitignore;
         let project = self.project.read(cx);
         self.last_worktree_root_id = project
             .visible_worktrees(cx)
@@ -2675,7 +2688,9 @@ impl ProjectPanel {
                     }
                 }
                 auto_folded_ancestors.clear();
-                visible_worktree_entries.push(entry.to_owned());
+                if !hide_gitignore || !entry.is_ignored {
+                    visible_worktree_entries.push(entry.to_owned());
+                }
                 let precedes_new_entry = if let Some(new_entry_id) = new_entry_parent_id {
                     entry.id == new_entry_id || {
                         self.ancestors.get(&entry.id).map_or(false, |entries| {
@@ -2688,7 +2703,7 @@ impl ProjectPanel {
                 } else {
                     false
                 };
-                if precedes_new_entry {
+                if precedes_new_entry && (!hide_gitignore || !entry.is_ignored) {
                     visible_worktree_entries.push(GitEntry {
                         entry: Entry {
                             id: NEW_ENTRY_ID,