[roll] Roll fuchsia [storage] Rename storage-host -> gpt

Moves //src/storage-host to //src/storage/gpt/component.  The component
is now named gpt2.cm (necessary to avoid collisions with the gpt.cm DF
component).

I also took this opportunity to clean up the storage assembly config:
- Make blob/data configuration non-optional since Fuchsia expects that
  FVM images always contain both a blob and data volume.  (The data
  volume is not actually included in the FVM image flashed to the
  device, but this configuration tells fshost how to create the data
  volume when absent.)
- Add GptMode to the board arguments, describing whether the system
  will allow 0, 1, or N GPT devices to be bound.  This will be used
  to exclude the GPT component from the build on systems that don't use
  the GPT.  For now, this defaults to GptMode::Enabled, which permits
  one device, and `gpt_all` was rolled into GptMode as AllowMultiple.
  For a soft migration, `gpt_all` is still supported.
- Clean up the fshost config variants and associated AIBs so that each
  valid system configuration corresponds to a single "fshost_*" input
  bundle.  There are three configs with storage_host we care about:
  - fshost_storage_host_fxfs
  - fshost_storage_host_gpt_fvm_minfs
  - fshost_storage_host_fvm_minfs

Original-Bug: 372949226
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1163478
Original-Revision: 21ebcf0ba901276121ae1a2a23f77fb2a7e275b5
GitOrigin-RevId: bab5f32a280ab36447c0b1f9d119fadf35a0036a
Change-Id: I3dd0462650ee767ff56835bbba1773d2a4fab298