storage/virtio-scsi: add missing resource_reference types for target_name_ref and controller_name_ref

[RedZapdos123]

Description:

While checking the broader resource reference annotation gaps tracked in #379, I found two additional straightforward misses in storage/frontend_virtio_scsi.proto.

These fields represent other resources, but they do not currently declare (google.api.resource_reference).type:

• storage/frontend_virtio_scsi.proto:190 - VirtioScsiLun.target_name_ref
• storage/frontend_virtio_scsi.proto:421 - StatsVirtioScsiLunRequest.controller_name_ref

Why this is an issue:

The same file already uses explicit resource reference typing for related fields, for example:

• CreateVirtioScsiLunRequest.parent uses child_type = "opi_api.storage.v1/VirtioScsiTarget"
• DeleteVirtioScsiLunRequest.name uses type = "opi_api.storage.v1/VirtioScsiLun"
• CreateVirtioScsiTargetRequest.parent uses child_type = "opi_api.storage.v1/VirtioScsiController"

So these two fields stand out as inconsistent with the rest of the schema and with AIP-122 guidance for fields that reference another resource.

Expected fix:

Add the missing resource reference annotations:

• target_name_ref -> opi_api.storage.v1/VirtioScsiTarget
• controller_name_ref -> opi_api.storage.v1/VirtioScsiController

Issue inspection:

Inspect storage/frontend_virtio_scsi.proto and compare:

• line 190: string target_name_ref = 2 [(google.api.field_behavior) = REQUIRED];
• line 421: string controller_name_ref = 2 [(google.api.field_behavior) = OPTIONAL];

against nearby fields in the same file that already include (google.api.resource_reference) metadata.

[RedZapdos123]

Opened a PR to resolve this issue.