project_search: Add button to collapse/expand all excerpts (#41654)

<img width="500" height="834" alt="Screenshot 2025-11-03 at 12  59@2x"
src="https://github.com/user-attachments/assets/15c5e1fc-2291-41b4-9eec-a8cfa5a446c7"
/>

Releases Note:

- Added a button that allows to expand/collapse all project search
excerpts at once.

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Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

assets/keymaps/default-linux.json

@@ -407,6 +407,7 @@
     "bindings": {
       "escape": "project_search::ToggleFocus",
       "shift-find": "search::FocusSearch",
+      "shift-enter": "project_search::ToggleAllSearchResults",
       "ctrl-shift-f": "search::FocusSearch",
       "ctrl-shift-h": "search::ToggleReplace",
       "alt-ctrl-g": "search::ToggleRegex",
@@ -479,6 +480,7 @@
       "alt-w": "search::ToggleWholeWord",
       "alt-find": "project_search::ToggleFilters",
       "alt-ctrl-f": "project_search::ToggleFilters",
+      "shift-enter": "project_search::ToggleAllSearchResults",
       "ctrl-alt-shift-r": "search::ToggleRegex",
       "ctrl-alt-shift-x": "search::ToggleRegex",
       "alt-r": "search::ToggleRegex",