go/mirko: add SQL migrations machinery

This uses github.com/golang-migrate/migrate and adds a Source that
allows using go_embed data files.

We also provide a test/example.

Change-Id: Icd2b6c7f7d0f728073b3fdf39b432b33ce61a3cd
diff --git a/go/mirko/tests/sql/BUILD.bazel b/go/mirko/tests/sql/BUILD.bazel
new file mode 100644
index 0000000..5831dcd
--- /dev/null
+++ b/go/mirko/tests/sql/BUILD.bazel
@@ -0,0 +1,10 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_test")
+
+go_test(
+    name = "go_default_test",
+    srcs = ["sql_test.go"],
+    deps = [
+        "//go/mirko/tests/sql/migrations:go_default_library",
+        "@com_github_golang_migrate_migrate_v4//database/sqlite3:go_default_library",
+    ],
+)