libcamera: Replace plain pointers with std::unique<>

libcamera uses std::unique_ptr<> to simplify life time management of
objects and avoid leaks. For historical reasons there are a fair number
of plain pointers with manual memory management. Replace them with
std::unique_ptr<> when the conversion is simple.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>
Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>

Documentation/guides/application-developer.rst

@@ -279,7 +279,7 @@ as the parameter of the ``FrameBufferAllocator::buffers()`` function.
 
 .. code:: cpp
 
-   FrameBufferAllocator *allocator = new FrameBufferAllocator(camera);
+   auto allocator = std::make_unique<FrameBufferAllocator>(camera);
 
    for (StreamConfiguration &cfg : *config) {
        int ret = allocator->allocate(cfg.stream());
@@ -539,7 +539,7 @@ uses, so needs to do the following:
 
    camera->stop();
    allocator->free(stream);
-   delete allocator;
+   allocator.reset();
    camera->release();
    camera.reset();
    cm->stop();