refactor: miniooni should be outside of the engine (#206)

* refactor: miniooni should be outside of the engine

This is part of https://github.com/ooni/probe/issues/1335. We also need
to think whether we wanna keep libminiooni and miniooni separated.

The previous use case for having a top-level libminiooni was that of
enabling others to integrate miniooni into other binaries.

This was usegul when studying internet censorship in Spain in May 2020.

I am wondering whether we should be keeping this complexity. I am not
sure about this and probably we should be killing it.

(In any case, reducing complexity is not the objective of this diff,
since I would like instead to move things around with minimal changes
and make sure we have a ~good repository organization here.)

* fix: import in libminiooni

internal/libminiooni/libminiooni_integration_test.go

@@ -0,0 +1,16 @@
+package libminiooni_test
+
+import (
+	"testing"
+
+	"github.com/ooni/probe-cli/v3/internal/libminiooni"
+)
+
+func TestSimple(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	libminiooni.MainWithConfiguration("example", libminiooni.Options{
+		Yes: true,
+	})
+}