ipa: move libipa::Algorithm to ipa/ipu3/algorithms

The abstract Algorithm class was originally placed in libipa as an
attempt define a generic algorithm container. This was a little
optimistic and pushed a bit far too early.

Move the Algorithm class into the IPU3 which is the only user of the
class, as we adapt it to support modular algorithm components for the
IPU3.

Not documenting the namespace may cause issues with Doxygen in libipa.
The file libipa.cpp is thus created as an empty file for now, but we
can leverage it in the future to add more global libipa documentation,
and possibly code too.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/ipa/libipa/algorithm.h

@@ -1,24 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-/*
- * Copyright (C) 2021, Ideas On Board
- *
- * algorithm.h - ISP control algorithm interface
- */
-#ifndef __LIBCAMERA_IPA_LIBIPA_ALGORITHM_H__
-#define __LIBCAMERA_IPA_LIBIPA_ALGORITHM_H__
-
-namespace libcamera {
-
-namespace ipa {
-
-class Algorithm
-{
-public:
-	virtual ~Algorithm();
-};
-
-} /* namespace ipa */
-
-} /* namespace libcamera */
-
-#endif /* __LIBCAMERA_IPA_LIBIPA_ALGORITHM_H__ */