fastbootd: Support flashall with logical partitions.

Currently, fastboot flashall will try to flash every partition in the
image list. For devices with logical partitions, this will cause those
partitions to be flashed twice (once via super.img, and again for each
individual image). Additionally, super.img is needed to synchronize the
logical partition list, but it is only generated with "make dist",
making it inconvenient for most workflows.

This patch removes automatic flashing of super.img. Instead, devices
with a super partition must now generate a "super_empty.img"
describing the super geometry and logical partition layout. Before
flashing any other partitions, this image is used to ensure the device
has created all necessary logical partitions.

Additionally, before flashing (but after updating super), all logical
partitions that will be flashed are resized to 0. This ensures that
logical partitions will receive more optimal space allocation.

Finally, during flashing of individual images, logical partitions are
resized to the image size, since they do not have hardcoded sizes in the
build.

Bug: 78793464
Test: fastboot flashall can flash vendor, product, product_services
      without a make dist/super.img.

Change-Id: I18c2291e0d0cb10de729c5646b75ac84dde8c871