utils/generate-cyclonedx: mark host packages as excluded

Mark Buildroot's host packages as 'excluded' with the scope
property [1]. The excluded scope is defined like the following:

> Components that are excluded provide the ability to document component
> usage for test and other non-runtime purposes. Excluded components are
> not reachable within a call graph at runtime.

This fits the usage of 'host' packages : a package without a runtime
purpose.

See the mailing list discussion around this property [2][3][4][5]

[1] https://cyclonedx.org/docs/1.6/json/#metadata_tools_oneOf_i0_components_items_scope
[2] https://lore.kernel.org/r/<de0bb761-ca88-4bc6-8d7b-6bd14e9d1cbe@cherry.de>
[3] https://lore.kernel.org/r/<20260409204208.302842-1-thomas.perale@mind.be>
[4] https://lore.kernel.org/r/<bd0f43c9-ebdc-4717-b8d4-783ec712bed2@cherry.de>
[5] https://lore.kernel.org/r/<176c5c42-50bc-4b39-a7b3-845b085f010e@rnout.be>

Signed-off-by: Thomas Perale <thomas.perale@mind.be>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>

utils/generate-cyclonedx

@@ -371,6 +371,9 @@ def cyclonedx_component(name, comp):
     return {
         "bom-ref": name,
         "type": "library",
+        **({
+            "scope": "excluded"
+        } if comp["type"] == "host" else {}),
         **({
             "name": comp["name"],
         } if "name" in comp else {}),