refactor: taskfile/ast package (#1450)

* refactor: ast package

* feat: read -> taskfile

* refactor: taskfile.Taskfile -> taskfile.Read

* refactor: move merge function back into taskfile package

* refactor: rename taskfile.go to read.go

taskfile/node.go

@@ -0,0 +1,44 @@
+package taskfile
+
+import (
+	"context"
+	"strings"
+
+	"github.com/go-task/task/v3/errors"
+	"github.com/go-task/task/v3/internal/experiments"
+)
+
+type Node interface {
+	Read(ctx context.Context) ([]byte, error)
+	Parent() Node
+	Location() string
+	Optional() bool
+	Remote() bool
+}
+
+func NewNode(
+	uri string,
+	insecure bool,
+	opts ...NodeOption,
+) (Node, error) {
+	var node Node
+	var err error
+	switch getScheme(uri) {
+	case "http", "https":
+		node, err = NewHTTPNode(uri, insecure, opts...)
+	default:
+		// If no other scheme matches, we assume it's a file
+		node, err = NewFileNode(uri, opts...)
+	}
+	if node.Remote() && !experiments.RemoteTaskfiles {
+		return nil, errors.New("task: Remote taskfiles are not enabled. You can read more about this experiment and how to enable it at https://ast.dev/experiments/remote-taskfiles")
+	}
+	return node, err
+}
+
+func getScheme(uri string) string {
+	if i := strings.Index(uri, "://"); i != -1 {
+		return uri[:i]
+	}
+	return ""
+}