DEV: Add initial structure for migrations-tooling

migrations/spec/import_spec.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+RSpec.describe "Migrations::Import" do
+  subject(:cli) { system "migrations/import" }
+
+  it "works" do
+    expect { cli }.to output(
+      include("Importing into Discourse #{Discourse::VERSION::STRING}"),
+    ).to_stdout_from_any_process
+  end
+end