chore: adds directory structure for engine and experimental packages (#234)

This adds placeholder directories for the `engine` and `experimental`
packages. This structure is intended to support future development and
organization of code related to the engine's runtime and experimental
features.

Author: jkongie

engine/cld/runtime/runtime.go

@@ -0,0 +1,4 @@
+// Package runtime is the runtime for the CLD engine. It is responsible for providing methods to load the Environment
+// and execute changesets using a predefined folder based approach called 'domains'.
+
+package runtime

engine/test/runtime/runtime.go

@@ -0,0 +1,4 @@
+// Package runtime is the runtime for the test engine. It is responsible for providing methods to load the Environment
+// and execute changesets for unit and integration tests.
+
+package runtime

experimental/experimental.go

@@ -0,0 +1,4 @@
+// Package experimental is used to experiment with new features and ideas. Any code in this package is not guaranteed to be stable
+// or working, and may be change or removed at any time.
+
+package experimental