bridging: Add creation timestamps

This small feature will help to checking the bridge's status to
figure out which bridge is in old/zombie or not. Also added
detail items for the 'bridge show *' cli to provide more detail
info. And added creation item to the ARI as well.

ASTERISK-28279

Change-Id: I460238c488eca4d216b9176576211cb03286e040

res/ari/ari_model_validators.h

@@ -1488,6 +1488,7 @@ ari_validator ast_ari_validate_application_fn(void);
  * - bridge_class: string (required)
  * - bridge_type: string (required)
  * - channels: List[string] (required)
+ * - creationtime: Date (required)
  * - creator: string (required)
  * - id: string (required)
  * - name: string (required)