lib/oe/recipeutils: add a parse_recipe_simple() function

lib/oe/recipeutils: add a parse_recipe_simple() function

Add a function that simply parses a recipe by name and optionally the
bbappends that apply to it. (Note that if you're using tinfoil you need
to have initialised it with config_only=False so that it can map the
recipe name to a recipe file.)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>