WIP: Spawn backend plugins v2 (#19835)

* WIP: Spawn backend plugins v2

* Add test for plugin version

* Fix support for SDK plugins

Co-authored-by: Kyle Brandt <kyle@kbrandt.com>
Co-authored-by: Marcus Olsson <olsson.e.marcus@gmail.com>
Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

* WIP: Draft PR for fork of V2 sdk / bi-directional support (#19890)

* temporary use export-datasource-plugin branch of grafana-plugin-sdk

* fix failing test

* remove debug (spew) lines

* misc cleanup

* add expressions feature toggle

* use latest grafana-plugin-sdk-go

pkg/plugins/datasource_plugin_test.go

@@ -0,0 +1,34 @@
+package plugins
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLoadDatasourceVersion(t *testing.T) {
+	t.Run("If plugin version is not set, it should be treated as plugin version one", func(t *testing.T) {
+		pluginJSON, _ := json.Marshal(DataSourcePlugin{})
+		datasourcePlugin := DataSourcePlugin{}
+		(&datasourcePlugin).Load(json.NewDecoder(bytes.NewReader(pluginJSON)), "/tmp")
+		assert.True(t, datasourcePlugin.isVersionOne())
+	})
+
+	t.Run("If plugin version is set to one, it should be treated as plugin version one", func(t *testing.T) {
+		pluginJSON, _ := json.Marshal(DataSourcePlugin{SDK: false})
+		datasourcePlugin := DataSourcePlugin{}
+		(&datasourcePlugin).Load(json.NewDecoder(bytes.NewReader(pluginJSON)), "/tmp")
+		assert.True(t, datasourcePlugin.isVersionOne())
+		assert.False(t, datasourcePlugin.SDK)
+	})
+
+	t.Run("If plugin version is set to two, it should not be treated as plugin version one", func(t *testing.T) {
+		pluginJSON, _ := json.Marshal(DataSourcePlugin{SDK: true})
+		datasourcePlugin := DataSourcePlugin{}
+		(&datasourcePlugin).Load(json.NewDecoder(bytes.NewReader(pluginJSON)), "/tmp")
+		assert.False(t, datasourcePlugin.isVersionOne())
+		assert.True(t, datasourcePlugin.SDK)
+	})
+}