libcamera: vector: Add a Span based constructor

When one wants to create a Vector from existing data, currently the only
way is via std::array. Add a Span based constructor to allow creation
from std::vectors and alike.

While at it, replace the manual loop with std::copy.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

include/libcamera/internal/vector.h

@@ -42,8 +42,12 @@ public:
 
 	constexpr Vector(const std::array<T, Rows> &data)
 	{
-		for (unsigned int i = 0; i < Rows; i++)
-			data_[i] = data[i];
+		std::copy(data.begin(), data.end(), data_.begin());
+	}
+
+	constexpr Vector(const Span<const T, Rows> data)
+	{
+		std::copy(data.begin(), data.end(), data_.begin());
 	}
 
 	const T &operator[](size_t i) const