Build boot images in bootclasspath_fragment/platform_bootclasspath

Moves the building of boot images from the dexpreopt_bootjars singleton
to the bootclasspath_fragment and platform_bootclasspath.

The art boot image is generated by the art-bootclasspath-fragment
module and the framework boot image by the platform-bootclasspath
module.

This does temporarly duplicate the generation of an identical boot
profile for each image. As part of the work to modularize the boot
image profile each image will have its own custom default boot profile.

Bug: 177892522
Bug: 186455808
Test: m droid and TreeHugger
Change-Id: I23cf05ec7648749b21c7cf6fcba282b46649a981