Trigger VSCode to rename after extract variable assist is applied

When the user applies the "Extract Variable" assist, the cursor is
positioned at the newly inserted variable. This commit adds a command
to the assist that triggers the rename action in VSCode. This way, the
user can quickly rename the variable after applying the assist.

Fixes part of: #17579

editors/code/src/client.ts

@@ -348,6 +348,7 @@ class ExperimentalFeatures implements lc.StaticFeature {
                     "rust-analyzer.showReferences",
                     "rust-analyzer.gotoLocation",
                     "editor.action.triggerParameterHints",
+                    "editor.action.rename",
                 ],
             },
             ...capabilities.experimental,