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

crates/ide-diagnostics/src/handlers/trait_impl_redundant_assoc_item.rs

@@ -98,7 +98,7 @@ fn quickfix_for_redundant_assoc_item(
         group: None,
         target: range,
         source_change: Some(source_change_builder.finish()),
-        trigger_signature_help: false,
+        command: None,
     }])
 }
 

crates/ide-diagnostics/src/handlers/typed_hole.rs

@@ -82,7 +82,7 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::TypedHole) -> Option<Vec<Assist>
                 original_range.file_id,
                 TextEdit::replace(original_range.range, code),
             )),
-            trigger_signature_help: false,
+            command: None,
         })
         .collect();
 

crates/ide-diagnostics/src/handlers/unresolved_field.rs

@@ -130,7 +130,7 @@ fn add_variant_to_union(
         group: None,
         target: error_range.range,
         source_change: Some(src_change_builder.finish()),
-        trigger_signature_help: false,
+        command: None,
     })
 }
 
@@ -173,7 +173,7 @@ fn add_field_to_struct_fix(
                 group: None,
                 target: error_range.range,
                 source_change: Some(src_change_builder.finish()),
-                trigger_signature_help: false,
+                command: None,
             })
         }
         None => {
@@ -204,7 +204,7 @@ fn add_field_to_struct_fix(
                 group: None,
                 target: error_range.range,
                 source_change: Some(src_change_builder.finish()),
-                trigger_signature_help: false,
+                command: None,
             })
         }
         Some(FieldList::TupleFieldList(_tuple)) => {
@@ -266,7 +266,7 @@ fn method_fix(
             file_id,
             TextEdit::insert(range.end(), "()".to_owned()),
         )),
-        trigger_signature_help: false,
+        command: None,
     })
 }
 #[cfg(test)]

crates/ide-diagnostics/src/handlers/unresolved_method.rs

@@ -108,7 +108,7 @@ fn field_fix(
             (file_id, TextEdit::insert(range.start(), "(".to_owned())),
             (file_id, TextEdit::insert(range.end(), ")".to_owned())),
         ])),
-        trigger_signature_help: false,
+        command: None,
     })
 }
 
@@ -191,7 +191,7 @@ fn assoc_func_fix(ctx: &DiagnosticsContext<'_>, d: &hir::UnresolvedMethodCall) -
                 file_id,
                 TextEdit::replace(range, assoc_func_call_expr_string),
             )),
-            trigger_signature_help: false,
+            command: None,
         })
     } else {
         None

crates/ide-diagnostics/src/handlers/unused_variables.rs

@@ -73,7 +73,7 @@ fn fixes(
             diagnostic_range.file_id,
             TextEdit::replace(name_range, format!("_{}", var_name.display(db))),
         )),
-        trigger_signature_help: false,
+        command: None,
     }])
 }
 

crates/ide-diagnostics/src/lib.rs

@@ -613,7 +613,7 @@ fn unresolved_fix(id: &'static str, label: &str, target: TextRange) -> Assist {
         group: None,
         target,
         source_change: None,
-        trigger_signature_help: false,
+        command: None,
     }
 }