[build] Change memory_layout from csv to yaml

I realized we don't need yet another format for configuration. As a
bonus, yaml also allows for a more descriptive file.

definitions/memory_layout.yaml

@@ -0,0 +1,17 @@
+---
+- name: linear
+  size: 64T
+  shared: true
+
+- name: bitmap
+  size: 1T
+  shared: true
+
+- name: heap
+  size: 64G
+
+- name: stacks
+  size: 64G
+
+- name: buffers
+  size: 64G