[Logs Explorer]: Update integration icons type (#162219)

## 📓 Summary

The integrations returned from the API have an `icons` property which is
an array of icon object descriptors.

The runtime validation on the clientside was not aligned with the type
of these icons, which are retrieved from the package manifest and have
some optional attributes, while the current implementation assumed all
the properties were mandatory.

This PR aligns the runtime type with the
[PackageSpecIcon](https://github.com/elastic/kibana/blob/main/x-pack/plugins/fleet/common/types/models/package_spec.ts#L114)
type.

<img width="314" alt="Screenshot 2023-07-19 at 11 08 01"
src="ff51bad6-89dd-44f3-a959-24d6717db235">
<img width="315" alt="Screenshot 2023-07-19 at 11 08 18"
src="10cb05bc-c138-4c03-9d8b-74f5a4b7aab0">

Co-authored-by: Marco Antonio Ghiani <marcoantonio.ghiani@elastic.co>

x-pack/plugins/discover_log_explorer/common/datasets/types.ts

@@ -25,6 +25,17 @@ const integrationStatusRT = rt.keyof({
   install_failed: null,
 });
 
+const iconRT = rt.intersection([
+  rt.type({
+    src: rt.string,
+  }),
+  rt.partial({
+    title: rt.string,
+    size: rt.string,
+    type: rt.string,
+  }),
+]);
+
 export const integrationRT = rt.intersection([
   rt.type({
     name: rt.string,
@@ -34,17 +45,7 @@ export const integrationRT = rt.intersection([
   }),
   rt.partial({
     title: rt.union([rt.string, rt.undefined]),
-    icons: rt.union([
-      rt.array(
-        rt.type({
-          src: rt.string,
-          title: rt.string,
-          size: rt.string,
-          type: rt.string,
-        })
-      ),
-      rt.undefined,
-    ]),
+    icons: rt.union([rt.array(iconRT), rt.undefined]),
     description: rt.union([rt.string, rt.undefined]),
   }),
 ]);