libcamera: pixel_format: Replace hex with format names

Print format names defined in formats namespace instead of the hex
values in toString() as they are easier to comprehend. For this add
a property of 'name' in PixelFormatInfo' so as to map the formats
with their names. Print fourcc for formats which are not used in
libcamera.

Signed-off-by: Kaaira Gupta <kgupta@es.iitr.ac.in>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

test/meson.build

@@ -34,6 +34,7 @@ internal_tests = [
     ['message',                         'message.cpp'],
     ['object',                          'object.cpp'],
     ['object-invoke',                   'object-invoke.cpp'],
+    ['pixel-format',                    'pixel-format.cpp'],
     ['signal-threads',                  'signal-threads.cpp'],
     ['threads',                         'threads.cpp'],
     ['timer',                           'timer.cpp'],