Add preview tabs (#9125)

This PR implements the preview tabs feature from VSCode.
More details and thanks for the head start of the implementation here
#6782.

Here is what I have observed from using the vscode implementation ([x]
-> already implemented):
- [x] Single click on project file opens tab as preview
- [x] Double click on item in project panel opens tab as permanent
- [x] Double click on the tab makes it permanent
- [x] Navigating away from the tab makes the tab permanent and the new
tab is shown as preview (e.g. GoToReference)
- [x] Existing preview tab is reused when opening a new tab
- [x] Dragging tab to the same/another panel makes the tab permanent
- [x] Opening a tab from the file finder makes the tab permanent
- [x] Editing a preview tab will make the tab permanent
- [x] Using the space key in the project panel opens the tab as preview
- [x] Handle navigation history correctly (restore a preview tab as
preview as well)
- [x] Restore preview tabs after restarting
- [x] Support opening files from file finder in preview mode (vscode:
"Enable Preview From Quick Open")
 
I need to do some more testing of the vscode implementation, there might
be other behaviors/workflows which im not aware of that open an item as
preview/make them permanent.

Showcase:


https://github.com/zed-industries/zed/assets/53836821/9be16515-c740-4905-bea1-88871112ef86


TODOs
- [x] Provide `enable_preview_tabs` setting
- [x] Write some tests
- [x] How should we handle this in collaboration mode (have not tested
the behavior so far)
- [x] Keyboard driven usage (probably need workspace commands)
- [x] Register `TogglePreviewTab` only when setting enabled?
- [x] Render preview tabs in tab switcher as italic
- [x] Render preview tabs in image viewer as italic
- [x] Should this be enabled by default (it is the default behavior in
VSCode)?
- [x] Docs

Future improvements (out of scope for now):
- Support preview mode for find all references and possibly other
multibuffers (VSCode: "Enable Preview From Code Navigation")


Release Notes:

- Added preview tabs
([#4922](https://github.com/zed-industries/zed/issues/4922)).

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/file_finder/Cargo.toml

@@ -22,6 +22,7 @@ itertools = "0.11"
 menu.workspace = true
 picker.workspace = true
 project.workspace = true
+settings.workspace = true
 text.workspace = true
 theme.workspace = true
 ui.workspace = true

crates/file_finder/src/file_finder.rs

@@ -12,6 +12,7 @@ use gpui::{
 use itertools::Itertools;
 use picker::{Picker, PickerDelegate};
 use project::{PathMatchCandidateSet, Project, ProjectPath, WorktreeId};
+use settings::Settings;
 use std::{
     cmp,
     path::{Path, PathBuf},
@@ -23,7 +24,7 @@ use std::{
 use text::Point;
 use ui::{prelude::*, HighlightedLabel, ListItem, ListItemSpacing};
 use util::{paths::PathLikeWithPosition, post_inc, ResultExt};
-use workspace::{ModalView, Workspace};
+use workspace::{item::PreviewTabsSettings, ModalView, Workspace};
 
 actions!(file_finder, [Toggle, SelectPrev]);
 
@@ -782,13 +783,24 @@ impl PickerDelegate for FileFinderDelegate {
         if let Some(m) = self.matches.get(self.selected_index()) {
             if let Some(workspace) = self.workspace.upgrade() {
                 let open_task = workspace.update(cx, move |workspace, cx| {
-                    let split_or_open = |workspace: &mut Workspace, project_path, cx| {
-                        if secondary {
-                            workspace.split_path(project_path, cx)
-                        } else {
-                            workspace.open_path(project_path, None, true, cx)
-                        }
-                    };
+                    let split_or_open =
+                        |workspace: &mut Workspace,
+                         project_path,
+                         cx: &mut ViewContext<Workspace>| {
+                            let allow_preview =
+                                PreviewTabsSettings::get_global(cx).enable_preview_from_file_finder;
+                            if secondary {
+                                workspace.split_path_preview(project_path, allow_preview, cx)
+                            } else {
+                                workspace.open_path_preview(
+                                    project_path,
+                                    None,
+                                    true,
+                                    allow_preview,
+                                    cx,
+                                )
+                            }
+                        };
                     match m {
                         Match::History(history_match, _) => {
                             let worktree_id = history_match.project.worktree_id;