Add node_modules on master with up-to-date deps

GitHub Actions tutorials suggest that you should not commit Node.js crap
onto your master branch, but it's not like this action has a lot of
dependencies, and not being able to test "ilammy/msvc-dev-cmd@master" is
so annoying... Therefore, do

    npm install --only production

and commit the results.

node_modules/@actions/core/lib/command.d.ts

@@ -0,0 +1,16 @@
+interface CommandProperties {
+    [key: string]: any;
+}
+/**
+ * Commands
+ *
+ * Command Format:
+ *   ::name key=value,key=value::message
+ *
+ * Examples:
+ *   ::warning::This is the message
+ *   ::set-env name=MY_VAR::some value
+ */
+export declare function issueCommand(command: string, properties: CommandProperties, message: any): void;
+export declare function issue(name: string, message?: string): void;
+export {};