[452294] Set AlphaBasedSlidableImageAnchor the default

Set the AlphaBasedSlidableImageAnchor as a default choice for all the
figures which are ending up as being the "node plate" for Image based
styles.

Contributed anchor providers are still prefered when present.

Bug: 452294
Change-Id: Ic39a8abff2952b55da20daf72c34739e2c60ea73
Signed-off-by: Cedric Brun <cedric.brun@obeo.fr
Signed-off-by: Laurent Redor <laurent.redor@obeo.fr>
2 files changed