Move cncd/pipeline/pipeline/ to pipeline/ (#347)

* Refactor: move cncd/pipeline/ to pipeline/

* Refactor: move pipeline/pipeline/ to pipeline/

pipeline/backend/kubernetes/kubernetes.go

@@ -0,0 +1,61 @@
+package kubernetes
+
+import (
+	"context"
+	"io"
+
+	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+)
+
+type engine struct {
+	namespace string
+	endpoint  string
+	token     string
+}
+
+// New returns a new Kubernetes Engine.
+func New(namespace, endpoint, token string) backend.Engine {
+	return &engine{
+		namespace: namespace,
+		endpoint:  endpoint,
+		token:     token,
+	}
+}
+
+// Setup the pipeline environment.
+func (e *engine) Setup(context.Context, *backend.Config) error {
+	// POST /api/v1/namespaces
+	return nil
+}
+
+// Start the pipeline step.
+func (e *engine) Exec(context.Context, *backend.Step) error {
+	// POST /api/v1/namespaces/{namespace}/pods
+	return nil
+}
+
+// DEPRECATED
+// Kill the pipeline step.
+func (e *engine) Kill(context.Context, *backend.Step) error {
+	return nil
+}
+
+// Wait for the pipeline step to complete and returns
+// the completion results.
+func (e *engine) Wait(context.Context, *backend.Step) (*backend.State, error) {
+	// GET /api/v1/watch/namespaces/{namespace}/pods
+	// GET /api/v1/watch/namespaces/{namespace}/pods/{name}
+	return nil, nil
+}
+
+// Tail the pipeline step logs.
+func (e *engine) Tail(context.Context, *backend.Step) (io.ReadCloser, error) {
+	// GET /api/v1/namespaces/{namespace}/pods/{name}/log
+	return nil, nil
+}
+
+// Destroy the pipeline environment.
+func (e *engine) Destroy(context.Context, *backend.Config) error {
+	// DELETE /api/v1/namespaces/{name}
+	return nil
+}