feat(extensions): add unsigned integer extension types (u8, u16, u32, u64)

Author: kadinrabo

extensions/extension_types_numeric.yaml

@@ -0,0 +1,12 @@
+%YAML 1.2
+---
+urn: "extension:io.substrait:extension_types_numeric"
+types:
+  - name: u8
+    structure: {}
+  - name: u16
+    structure: {}
+  - name: u32
+    structure: {}
+  - name: u64
+    structure: {}