Support for MacOS

Hi there,

I've recently been attempting to use the `[kmsp11](https://github.com/GoogleCloudPlatform/kms-integrations/tree/master/kmsp11)` module on MacOS to self sign a test certificate using my HSM key with no luck. I've been following the guide [here](https://cloud.google.com/kms/docs/reference/pkcs11-openssl), successfully setting the engine, and setting the module as directed.

However, the result I get is:
```
openssl engine pkcs11 -t
(pkcs11) pkcs11 engine
[ available ]

openssl req -new -x509 -days 3650 -subj '/CN=test/' -sha512 -engine pkcs11 -keyform engine -key pkcs11:object=my-hsm-key > my-request.crt
Engine "pkcs11" set.
dlopen(/opt/homebrew/Cellar/openssl@3/3.1.4/lib/ossl-modules/libkmsp11.so, 0x0005): tried: '/opt/homebrew/Cellar/openssl@3/3.1.4/lib/ossl-modules/libkmsp11.so' (not a mach-o file)
```
I assume this is because of the shared object file type.

Is there any chance of getting some guidance for MacOS (and compatible module?) as part of the kmsp11 [user guide](https://github.com/GoogleCloudPlatform/kms-integrations/blob/master/kmsp11/docs/user_guide.md)?