Update selection when keeping/rejecting hunks (#27902)

Release Notes:

- N/A

assets/keymaps/default-linux.json

@@ -138,7 +138,7 @@
     }
   },
   {
-    "context": "Editor && !assistant_diff",
+    "context": "Editor && !agent_diff",
     "bindings": {
       "ctrl-k ctrl-r": "git::Restore",
       "ctrl-alt-y": "git::ToggleStaged",
@@ -147,7 +147,7 @@
     }
   },
   {
-    "context": "AssistantDiff",
+    "context": "AgentDiff",
     "bindings": {
       "ctrl-y": "agent::Keep",
       "ctrl-k ctrl-r": "agent::Reject"
@@ -645,7 +645,7 @@
     "bindings": {
       "enter": "agent::Chat",
       "ctrl-i": "agent::ToggleProfileSelector",
-      "shift-ctrl-r": "agent::OpenAssistantDiff"
+      "shift-ctrl-r": "agent::OpenAgentDiff"
     }
   },
   {

assets/keymaps/default-macos.json

@@ -228,7 +228,7 @@
     }
   },
   {
-    "context": "Editor && !assistant_diff",
+    "context": "Editor && !agent_diff",
     "use_key_equivalents": true,
     "bindings": {
       "cmd-alt-z": "git::Restore",
@@ -238,7 +238,7 @@
     }
   },
   {
-    "context": "AssistantDiff",
+    "context": "AgentDiff",
     "use_key_equivalents": true,
     "bindings": {
       "cmd-y": "agent::Keep",
@@ -305,7 +305,7 @@
     "bindings": {
       "enter": "agent::Chat",
       "cmd-i": "agent::ToggleProfileSelector",
-      "shift-ctrl-r": "agent::OpenAssistantDiff"
+      "shift-ctrl-r": "agent::OpenAgentDiff"
     }
   },
   {