libcamera: request: Add operator<<()

With the recent addition of operator<<() in most libcamera core classes
to replace usage of the toString() function the Request class was left
behind.

Add operator<<() for the Request class and reimplement toString().

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/request.h

@@ -9,6 +9,7 @@
 
 #include <map>
 #include <memory>
+#include <ostream>
 #include <stdint.h>
 #include <string>
 #include <unordered_set>
@@ -75,4 +76,6 @@ private:
 	Status status_;
 };
 
+std::ostream &operator<<(std::ostream &out, const Request &r);
+
 } /* namespace libcamera */