runtime: support legacy Pipelines in new execution engine

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

plan/task/pipeline.go

@@ -0,0 +1,27 @@
+package task
+
+import (
+	"context"
+
+	"go.dagger.io/dagger/compiler"
+	"go.dagger.io/dagger/environment"
+	"go.dagger.io/dagger/plancontext"
+	"go.dagger.io/dagger/solver"
+)
+
+func init() {
+	Register("#up", func() Task { return &pipelineTask{} })
+}
+
+// pipelineTask is an adapter for legacy pipelines (`#up`).
+// FIXME: remove once fully migrated to Europa.
+type pipelineTask struct {
+}
+
+func (c pipelineTask) Run(ctx context.Context, pctx *plancontext.Context, s solver.Solver, v *compiler.Value) (*compiler.Value, error) {
+	p := environment.NewPipeline(v, s, pctx)
+	if err := p.Run(ctx); err != nil {
+		return nil, err
+	}
+	return p.Computed(), nil
+}