Make BufferSearch less wide (#10459)

This also adds some "responsiveness" so that UI elements are hidden
before everything has to be occluded

Release Notes:

- Improved search UI. It now works in narrower panes, and avoids
scrolling the editor on open.

<img width="899" alt="Screenshot 2024-04-11 at 21 33 17"
src="https://github.com/zed-industries/zed/assets/94272/44b95d4f-08d6-4c40-a175-0e594402ca01">
<img width="508" alt="Screenshot 2024-04-11 at 21 33 45"
src="https://github.com/zed-industries/zed/assets/94272/baf4638d-427b-43e6-ad67-13d43f0f18a2">
<img width="361" alt="Screenshot 2024-04-11 at 21 34 00"
src="https://github.com/zed-industries/zed/assets/94272/ff60b561-2f77-49c0-9df7-e26227fe9225">
<img width="348" alt="Screenshot 2024-04-11 at 21 37 03"
src="https://github.com/zed-industries/zed/assets/94272/a2a700a2-ce99-41bd-bf47-9b14d7082b0e">

assets/keymaps/default-linux.json

@@ -212,7 +212,6 @@
       "enter": "search::SelectNextMatch",
       "shift-enter": "search::SelectPrevMatch",
       "alt-enter": "search::SelectAllMatches",
-      "alt-tab": "search::CycleMode",
       "ctrl-f": "search::FocusSearch",
       "ctrl-h": "search::ToggleReplace"
     }
@@ -235,11 +234,10 @@
     "context": "ProjectSearchBar",
     "bindings": {
       "escape": "project_search::ToggleFocus",
-      "alt-tab": "search::CycleMode",
       "ctrl-shift-f": "search::FocusSearch",
       "ctrl-shift-h": "search::ToggleReplace",
-      "alt-ctrl-g": "search::ActivateRegexMode",
-      "alt-ctrl-x": "search::ActivateTextMode"
+      "alt-ctrl-g": "search::ToggleRegex",
+      "alt-ctrl-x": "search::ToggleRegex"
     }
   },
   {
@@ -260,10 +258,9 @@
     "context": "ProjectSearchView",
     "bindings": {
       "escape": "project_search::ToggleFocus",
-      "alt-tab": "search::CycleMode",
       "ctrl-shift-h": "search::ToggleReplace",
-      "alt-ctrl-g": "search::ActivateRegexMode",
-      "alt-ctrl-x": "search::ActivateTextMode"
+      "alt-ctrl-g": "search::ToggleRegex",
+      "alt-ctrl-x": "search::ToggleRegex"
     }
   },
   {
@@ -283,10 +280,10 @@
       "alt-enter": "search::SelectAllMatches",
       "alt-c": "search::ToggleCaseSensitive",
       "alt-w": "search::ToggleWholeWord",
-      "alt-r": "search::CycleMode",
+      "alt-r": "search::ToggleRegex",
       "alt-ctrl-f": "project_search::ToggleFilters",
-      "ctrl-alt-shift-r": "search::ActivateRegexMode",
-      "ctrl-alt-shift-x": "search::ActivateTextMode"
+      "ctrl-alt-shift-r": "search::ToggleRegex",
+      "ctrl-alt-shift-x": "search::ToggleRegex"
     }
   },
   // Bindings from VS Code