Redact sensitive values in stream_data rpcauth logs

[sfc-gh-elinardi]

#343 doesn't handle proxy anypb messages, so they don't get redacted.

This PR adds anypb log redaction by unmarshaling its content and redact it
Testing

{
    "caller": {
        "file": "rpcauth.go",
        "line": 128
    },
    "input": {
        "environment": null,
        "extensions": null,
        "host": {
            "cert": null,
            "net": {
                "address": "127.0.0.1",
                "network": "tcp",
                "port": "50043"
            },
            "principal": null
        },
        "message": {
            "stream_data": {
                "payload": {
                    "@type": "type.googleapis.com/HTTPOverRPC.HostHTTPRequest",
                    "hostname": "...",
                    "port": ...,
                    "protocol": "http",
                    "request": {
                        "headers": [
                            {
                                "key": "Accept",
                                "values": [
                                    "--REDACTED--"
                                ]
                            },
                            {
                                "key": "User-Agent",
                                "values": [
                                    "--REDACTED--"
                                ]
                            },
                            {
                                "key": "Authorization",
                                "values": [
                                    "--REDACTED--"
                                ]
                            },
                            {
                                "key": "Content-Type",
                                "values": [
                                    "--REDACTED--"
                                ]
                            }
                        ],
                        "method": "POST"
                    }
                },
                "stream_ids": [
                    "6992800144101358512"
                ]
            }
        },
        "method": "/Proxy.Proxy/Proxy",
    },
    "level": 2,
    "logger": "sansshell-proxy",
    "method": "/Proxy.Proxy/Proxy",
    "msg": "evaluating authz policy post hooks",
    "peer": {
        "cert": {
            "dnsnames": [
                "test.example.com"
            ],
            "issuer": "CN=example.com",
            "spiffeid": "",
            "subject": "CN=test.example.com"
        },
        "net": {
            "address": "127.0.0.1",
            "network": "tcp",
            "port": "52917"
        },
        "principal": null
    },
    "ts": "2023-10-16 15:52:41.328650"
}