feat(oonirun): implement OONIRun v1 (#843)

This diff adds support for running OONIRun v1 links.

Run with `miniooni` using:

```
./miniooni -i LINK oonirun
```

Part of https://github.com/ooni/probe/issues/2184

internal/oonirun/link.go

@@ -0,0 +1,92 @@
+package oonirun
+
+//
+// OONI Run v1 and v2 links
+//
+
+import (
+	"context"
+	"strings"
+
+	"github.com/ooni/probe-cli/v3/internal/model"
+)
+
+// LinkConfig contains config for an OONI Run link. You MUST fill all the fields that
+// are marked as MANDATORY, or the LinkConfig would cause crashes.
+type LinkConfig struct {
+	// AcceptChanges is OPTIONAL and tells this library that the user is
+	// okay with running a new or modified OONI Run link without previously
+	// reviewing what it contains or what has changed.
+	AcceptChanges bool
+
+	// Annotations contains OPTIONAL Annotations for the experiment.
+	Annotations map[string]string
+
+	// KVStore is the MANDATORY key-value store to use to keep track of
+	// OONI Run links and know when they are new or modified.
+	KVStore model.KeyValueStore
+
+	// MaxRuntime is the OPTIONAL maximum runtime in seconds.
+	MaxRuntime int64
+
+	// NoCollector OPTIONALLY indicates we should not be using any collector.
+	NoCollector bool
+
+	// NoJSON OPTIONALLY indicates we don't want to save measurements to a JSON file.
+	NoJSON bool
+
+	// Random OPTIONALLY indicates we should randomize inputs.
+	Random bool
+
+	// ReportFile is the MANDATORY file in which to save reports, which is only
+	// used when noJSON is set to false.
+	ReportFile string
+
+	// Session is the MANDATORY Session to use.
+	Session Session
+}
+
+// LinkRunner knows how to run an OONI Run v1 or v2 link.
+type LinkRunner interface {
+	Run(ctx context.Context) error
+}
+
+// linkRunner implements LinkRunner.
+type linkRunner struct {
+	config *LinkConfig
+	f      func(ctx context.Context, config *LinkConfig, URL string) error
+	url    string
+}
+
+// Run implements LinkRunner.Run.
+func (lr *linkRunner) Run(ctx context.Context) error {
+	return lr.f(ctx, lr.config, lr.url)
+}
+
+// NewLinkRunner creates a suitable link runner for the current config
+// and the given URL, which is one of the following:
+//
+// 1. OONI Run v1 link with https scheme (e.g., https://run.ooni.io/nettest?...)
+//
+// 2. OONI Run v1 link with ooni scheme (e.g., ooni://nettest?...)
+//
+// 3. arbitrary URL of the OONI Run v2 descriptor.
+func NewLinkRunner(c *LinkConfig, URL string) LinkRunner {
+	// TODO(bassosimone): add support for v2 deeplinks.
+	out := &linkRunner{
+		config: c,
+		f:      nil,
+		url:    URL,
+	}
+	switch {
+	case strings.HasPrefix(URL, "https://run.ooni.io/nettest"):
+		out.f = v1Measure
+	case strings.HasPrefix(URL, "ooni://nettest"):
+		out.f = v1Measure
+	default:
+		// TODO(bassosimone): this panic will go away when we merge
+		// the next patch which will implement v2.
+		panic("unsupported OONI Run link")
+	}
+	return out
+}