scripts: support list of images in build info

Add 'images' as valid list in build info schema.
This allow sysbuild and regular Zephyr images to populate build_info.yml
with images included in the build.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

scripts/schemas/build-schema.yml

@@ -56,6 +56,17 @@ mapping:
             type: seq
             sequence:
               - type: str
+      images:
+        type: seq
+        sequence:
+          - type: map
+            mapping:
+              name:
+                type: str
+              source-dir:
+                type: str
+              type:
+                type: str
       kconfig:
         type: map
         mapping: