fix: search_handler yields bytes and handle None in entity_extended_display

- search_handler yielded str from dumps() instead of bytes,
  causing TypeError in gunicorn when streaming search results
- entity_extended_display could return None for display/info
  causing AttributeError on .strip() when searching for SPs

Tested on pyFF 2.1.5 with gunicorn 25.1.0 and Python 3.12

Author: Stephan Krinetzki

src/pyff/api.py

@@ -462,7 +462,7 @@ def _response() -> Generator[bytes, bytes, None]:
         for e in entities:
             if in_loop:
                 yield b','
-            yield dumps(e)
+            yield dumps(e).encode('utf-8')
             in_loop = True
         yield b']'
 

src/pyff/samlmd.py

@@ -841,7 +841,7 @@ def entity_extended_display(entity, langs=None):
     if info == entity.get('entityID'):
         info = ''
 
-    return display.strip(), info.strip()
+    return (display or '').strip(), (info or '').strip()
 
 
 def entity_display_name(entity: Element, langs=None) -> str: