Add LogAsFilestream feature flag

Author: belimawr

elastic-agent-client.proto

@@ -226,13 +226,19 @@ message Features {
     google.protobuf.Struct source = 1;
 
     FQDNFeature fqdn = 2;
+    FeatureFlag LogRunAsFilestream = 3;
 }
 
 // FQDN feature flag indicates to use FQDN for host.name instead of hostname.
 message FQDNFeature {
     bool enabled = 1;
 }
 
+// FeatureFlag allows a feature flag to be enabled/disabled
+message FeatureFlag {
+    bool enabled = 1;
+}
+
 // Elastic APM TLS config
 message ElasticAPMTLS {
     bool skip_verify = 1;