openhcl: Add HvSintEnabled flag to UEFI config for aarch64 (#2715)

[pbarbuda]

Cherry-pick of #2715.

This flag enables an ACPI device whose purpose is to reserve an interrupt for a VMM to use for hypervisor SINTs on aarch64.

(cherry picked from commit 46b2e02)

[Copilot]

Pull request overview

Backports support for an HvSintEnabled UEFI configuration flag (primarily for aarch64) by plumbing a new boolean through GET platform settings and into the UEFI config blob flags.

Changes:

• Extends the UEFI Flags bitfield with hv_sint_enabled while preserving the overall u64 layout (reserved bits adjusted accordingly).
• Adds hv_sint_enabled to GET protocol/platform settings structs and threads it through the GET transport/client, GED device config, and resource resolver paths.
• Wires the new flag into underhill_core’s UEFI config writer (flags.set_hv_sint_enabled(...)).

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
vm/loader/src/uefi/config.rs	Adds hv_sint_enabled to the UEFI Flags bitfield and updates reserved bit count.
vm/devices/get/guest_emulation_transport/src/client.rs	Maps JSON hv_sint_enabled into the transport API General settings.
vm/devices/get/guest_emulation_transport/src/api.rs	Extends platform_settings::General with hv_sint_enabled.
vm/devices/get/guest_emulation_device/src/test_utilities.rs	Initializes hv_sint_enabled in test guest configs.
vm/devices/get/guest_emulation_device/src/resolver.rs	Passes hv_sint_enabled from resource handle into device config.
vm/devices/get/guest_emulation_device/src/lib.rs	Stores hv_sint_enabled in GuestConfig and serializes it into DPS v2 static settings.
vm/devices/get/get_resources/src/lib.rs	Adds hv_sint_enabled to the GED resource handle API.
vm/devices/get/get_protocol/src/dps_json.rs	Adds hv_sint_enabled to DPS v2 static JSON with #[serde(default)] for compatibility.
petri/src/vm/openvmm/construct.rs	Sets hv_sint_enabled: false in Petri GED construction.
openvmm/openvmm_entry/src/lib.rs	Sets hv_sint_enabled: false in CLI-based GED construction.
openhcl/underhill_core/src/worker.rs	Updates pattern match/destructure to include hv_sint_enabled.
openhcl/underhill_core/src/loader/mod.rs	Writes the new flag into the UEFI config blob (set_hv_sint_enabled).

[github-actions]

At least one Petri test failed.