Convert potential spaces in Memcache(d) key names

- Address https://github.com/friendica/friendica/issues/11630#issuecomment-1166475036
- Add test for space in cache keys

src/Core/Cache/Type/MemcacheCache.php

@@ -68,6 +68,17 @@ class MemcacheCache extends AbstractCache implements ICanCacheInMemory
 		}
 	}
 
+	/**
+	 * Memcache doesn't allow spaces in keys
+	 *
+	 * @param string $key
+	 * @return string
+	 */
+	protected function getCacheKey(string $key): string
+	{
+		return str_replace(' ', '_', parent::getCacheKey($key));
+	}
+
 	/**
 	 * (@inheritdoc)
 	 */

src/Core/Cache/Type/MemcachedCache.php

@@ -93,6 +93,17 @@ class MemcachedCache extends AbstractCache implements ICanCacheInMemory
 		}
 	}
 
+	/**
+	 * Memcached doesn't allow spaces in keys
+	 *
+	 * @param string $key
+	 * @return string
+	 */
+	protected function getCacheKey(string $key): string
+	{
+		return str_replace(' ', '_', parent::getCacheKey($key));
+	}
+
 	/**
 	 * (@inheritdoc)
 	 */