Allow hwasan variant for vendor_snapshot_static modules

vendor_snapshot_static modules can define hwasan variant as below:

vendor_snapshot_static {
    name: "libsnapshot",
    vendor: true,
    version: "33",
    arch: {
        arm64: {
            src: "libsnapshot.a",
            hwasan: {
                src: "libsnapshot.hwasan.a",
            },
        },
    },
}

Bug: 234772527
Test: m nothing
Change-Id: I0725028a4fdc302005d86f1e36561b98c0af623b