Switch project search deploy behavior to be isolated to a pane (#4072)

This adjusts the solution in
https://github.com/zed-industries/zed/pull/4014 to fix the double-focus
issue, allowing each pane's project search to work independently.

Release Notes:

- Changed the name of the `workspace::DeploySearch` action to
`pane::DeploySearch` and changed it's behavior to open a new search OR
focus an existing project search in the current pane.
(https://github.com/zed-industries/community/issues/2395)

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::DeploySearch",
+      "cmd-shift-f": "pane::DeploySearch",
       "cmd-k cmd-t": "theme_selector::Toggle",
       "cmd-k cmd-s": "zed::OpenKeymap",
       "cmd-t": "project_symbols::Toggle",