libcamera: geometry: SizeRange: Add toString()

It's useful to be able to print a string representation of a SizeRange
to the log or console, add a toString() method. While at it turn the
structure into a class as it contains functions as well as data.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/geometry.h

@@ -67,7 +67,9 @@ static inline bool operator>=(const Size &lhs, const Size &rhs)
 	return !(lhs < rhs);
 }
 
-struct SizeRange {
+class SizeRange
+{
+public:
 	SizeRange()
 	{
 	}
@@ -90,6 +92,8 @@ struct SizeRange {
 	{
 	}
 
+	std::string toString() const;
+
 	Size min;
 	Size max;
 	unsigned int hStep;