class/sdk-image: Provide 'sdk' for seamless sdk building
class/sdk-image: Provide 'sdk' for seamless sdk building

By proper configuration of PREFERRED_PROVIDER or DEFAULT_PREFERENCE,
building the proper sdk image does not require knowledge about the
name of the sdk recipe.

Signed-off-by: Esben Haabendal <c5ba3f1141bb30a64dd6c7e6726a53a85adc9442@prevas.dk>

sknsean/core,hundeboll/core,sknsean/core,hundeboll/core,sknsean/core,hundeboll/core,hundeboll/core,diorcety/oe-lite-core,sknsean/core,diorcety/oe-lite-core,sknsean/core