Does grpcurl support pulling a client certificate from the OS X Keychain?

This [answer](https://stackoverflow.com/a/73986026/391161) on Stackoverflow describes the following mechanism for using a client certificate from the OSX keychain, which I verified works for me.

```
CURL_SSL_BACKEND=secure-transport curl --cert "My Cert" https://10.0.1.101/
```

Is there an equivalent option or env var in `grpcurl` that allows it to pull a client certificate from the OSX keychain?

Start by reviewing grpcurl's existing client-certificate options and compare them with the documented CURL_SSL_BACKEND=secure-transport curl mechanism. Determine whether OS X Keychain certificates can be exposed through the current TLS path, and define the option or environment variable that would make this work. The issue names no files or tests, so completion criteria will need to be established.

Written by the indexing model from the issue text.