Keyboard navigation and setting persistence for project search (#2996)

Enable keyboard shortcuts for Project Search modes, and ensure project
search settings are persisted search to search.

Release Notes:

- Added alt-cmd-s to Toggle Semantic Search Mode
- Added alt-cmd-g to Toggle Regex Search Mode
- Added alt-cmd-x to Toggle Text Search Mode
- Defaulted new project searches to using last used search mode and
settings.

assets/keymaps/default.json

@@ -248,7 +248,10 @@
     "context": "ProjectSearchBar",
     "bindings": {
       "escape": "project_search::ToggleFocus",
-      "alt-tab": "search::CycleMode"
+      "alt-tab": "search::CycleMode",
+      "alt-cmd-g": "search::ActivateRegexMode",
+      "alt-cmd-s": "search::ActivateSemanticMode",
+      "alt-cmd-x": "search::ActivateTextMode"
     }
   },
   {
@@ -262,7 +265,10 @@
     "context": "ProjectSearchView",
     "bindings": {
       "escape": "project_search::ToggleFocus",
-      "alt-tab": "search::CycleMode"
+      "alt-tab": "search::CycleMode",
+      "alt-cmd-g": "search::ActivateRegexMode",
+      "alt-cmd-s": "search::ActivateSemanticMode",
+      "alt-cmd-x": "search::ActivateTextMode"
     }
   },
   {
@@ -275,7 +281,10 @@
       "alt-cmd-c": "search::ToggleCaseSensitive",
       "alt-cmd-w": "search::ToggleWholeWord",
       "alt-tab": "search::CycleMode",
-      "alt-cmd-f": "project_search::ToggleFilters"
+      "alt-cmd-f": "project_search::ToggleFilters",
+      "alt-cmd-g": "search::ActivateRegexMode",
+      "alt-cmd-s": "search::ActivateSemanticMode",
+      "alt-cmd-x": "search::ActivateTextMode"
     }
   },
   // Bindings from VS Code

assets/settings/default.json

@@ -370,8 +370,7 @@
   },
   // Difference settings for semantic_index
   "semantic_index": {
-    "enabled": false,
-    "reindexing_delay_seconds": 600
+    "enabled": false
   },
   // Different settings for specific languages.
   "languages": {