Return back old project search behavior as default.

Add a `workspace::DeploySearch` action and use it as a default for "cmd-shift-f" binding.
This action opens existing search tab if it exists, or creates a new one otherwise.
`workspace::NewSearch` action is still available and always opens an existing search tab.

assets/keymaps/default.json

@@ -402,7 +402,7 @@
       "cmd-r": "workspace::ToggleRightDock",
       "cmd-j": "workspace::ToggleBottomDock",
       "alt-cmd-y": "workspace::CloseAllDocks",
-      "cmd-shift-f": "workspace::NewSearch",
+      "cmd-shift-f": "workspace::DeploySearch",
       "cmd-k cmd-t": "theme_selector::Toggle",
       "cmd-k cmd-s": "zed::OpenKeymap",
       "cmd-t": "project_symbols::Toggle",