Expose more CPU features on WSL1 on arm64

On some Arm hardware with ARMv8.4-A:

$ lscpu
Architecture: aarch64
CPU op-mode(s): 64-bit
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 4
Vendor ID: ARM
Model: 0
Model name: Cortex-A57
Stepping: r1p0
CPU max MHz: 1000.0000
BogoMIPS: 1000
Hypervisor vendor: Windows Subsystem for Linux
Virtualization type: container
Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32

on WSL1. This does not represent the native feature set of the processor and reports it as a Cortex-A57. A more real feature for that processor is:

$ lscpu
Architecture: aarch64
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Thread(s) per core: 1
Core(s) per socket: 4
Socket(s): 1
NUMA node(s): 1
Vendor ID: ARM
Model: 0
Stepping: r0p0
BogoMIPS: 48.00
NUMA node0 CPU(s): 0,1
Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm ssbs

with a Linux installation the same hardware.

This notably prevents apps from even using Armv8.1-A atomics support on WSL1 for that hardware.

No source files or tests are identified. Start by reproducing the WSL1 arm64 lscpu output and comparing it with the native Linux output; done means WSL1 exposes the processor's supported model and CPU feature flags, including Armv8.1-A atomics.