recipeutils: bbappend_recipe: add a way to specify the name of the file to add

recipeutils: bbappend_recipe: add a way to specify the name of the file to add

bbappend_recipe can take a dict of source files to add to SRC_URI where
the key is the full path to the file to be added and the value is a dict

Add a new optionnal entry "newname" to specify the name of the newly added file

Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>