ggml-virtgpu: improve the reliability of the code (llama/19846)

ggml-virtgpu: improve the reliability of the code (llama/19846)

* ggml-virtgpu-backend: validate the consistency of the received objects

This patch adds consistency checks in the
ggml-virtgpu-backend (running on the host side) to ensure that the
data received from the guest is consistent (valid pointers, valid
sizes and offsets).

* ggml-virtgpu-backend: add fallback/skips for optional ggml backend methods

```
  1. bck->iface.synchronize(bck)
  2. buft->iface.get_alloc_size(buft, op)
  3. buft->iface.get_max_size(buft)
```

these three methods are optional in the GGML interface. `get_max_size`
was already properly defaulted, but `backend sychronize` and `butf
get_max_size` would have segfaulted the backend if not implemented.

* ggml-virtgpu-backend: fix log format missing argument

* ggml-virtgpu-backend: improve the abort message

* ggml-virtgpu-backend: more safety checks

* ggml-virtgpu-backend: new error code

* ggml-virtgpu-backend: initialize all the error codes

* ggml-virtgpu: add a missing comment generated by the code generator

* ggml-virtgpu: add the '[virtgpu]' prefix to the device/buffer names

* ggml-virtgpu: apir_device_buffer_from_ptr: improve the error message

* ggml-virtgpu: shared: make it match the latest api_remoting.h of Virglrenderer APIR

(still unmerged)

* ggml-virtgpu: update the code generator to have dispatch_command_name in a host/guest shared file

* ggml-virtgpu: REMOTE_CALL: fail if the backend returns an error

* docs/backend/VirtGPU.md: indicate that the RAM+VRAM size is limed to 64 GB with libkrun

* ggml-virtgpu: turn off clang-format header ordering for some of the files

Compilation breaks when ordered alphabetically.

* ggml-virtgpu: clang-format

* ggml-virtgpu/backend/shared/api_remoting: better comments for the APIR return codes