feat(admin): upload instance branding images (#3476)

fluxer_admin/tests/api_deserialization.rs

@@ -1281,3 +1281,28 @@ fn deserialize_guild_threads_response() {
             .is_some_and(|m| m.archived && !m.locked)
     );
 }
+
+#[test]
+fn branding_asset_upload_request_matches_the_generated_contract() {
+    for kind in types::BrandingAssetKind::ALL {
+        for image in [Some("data:image/png;base64,iVBORw0KGgo=".to_owned()), None] {
+            let request = types::BrandingAssetUploadRequest {
+                kind,
+                image: image.clone(),
+            };
+            let value = serde_json::to_value(&request).unwrap();
+            assert_eq!(
+                value,
+                serde_json::json!({"kind": kind.as_str(), "image": image})
+            );
+            let generated: generated_types::BrandingAssetUploadRequest =
+                serde_json::from_value(value.clone()).expect("generated branding asset contract");
+            assert_eq!(
+                serde_json::to_value(generated).unwrap()["kind"],
+                value["kind"]
+            );
+            assert_eq!(types::BrandingAssetKind::parse(kind.as_str()), Some(kind));
+        }
+    }
+    assert_eq!(types::BrandingAssetKind::parse("banner"), None);
+}