res/stasis: Add CLI commands for displaying/debugging ARI apps

This patch adds three new CLI commands:
 - ari show apps: list the registered ARI applications
 - ari show app: show detailed information about an ARI application
 - ari set debug: dump events being sent to an ARI application

Note that while these CLI commands live in the res_stasis module, we use
the 'ari' family for these commands. This was done as most users of
Asterisk aren't aware of the semantic differences between ARI and
res_stasis, and some 'ari' CLI commands already exist.

ASTERISK-26488 #close

Change-Id: I51ad6ff0cabee0d69db06858c13f18b1c513c9f5

include/asterisk/stasis_app.h

@@ -76,6 +76,16 @@ typedef void (*stasis_app_cb)(void *data, const char *app_name,
  */
 struct ao2_container *stasis_app_get_all(void);
 
+/*!
+ * \brief Retrieve a handle to a Stasis application by its name
+ *
+ * \param name The name of the registered Stasis application
+ *
+ * \return \c stasis_app on success.
+ * \return \c NULL on error.
+ */
+struct stasis_app *stasis_app_get_by_name(const char *name);
+
 /*!
  * \brief Register a new Stasis application.
  *