feat(client): searchStore takes provider + namespace filter params

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/src/hub_client.dart

@@ -518,6 +518,8 @@ class HubClient {
     String category = '',
     String tag = '',
     String status = '',
+    String provider = '',
+    String namespace = '',
     int limit = 50,
   }) async {
     final r = await _admin.searchStore(pb.SearchStoreRequest(
@@ -525,6 +527,8 @@ class HubClient {
       category: category,
       tag: tag,
       status: status,
+      provider: provider,
+      namespace: namespace,
       limit: limit,
     ));
     return r.entries;