[COMPLIANCE] Add Copyright and License Headers (#26)

Co-authored-by: hashicorp-copywrite[bot] <110428419+hashicorp-copywrite[bot]@users.noreply.github.com>

plugin/network_processor.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package plugin
 
 import (

plugin/vm_processor.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package plugin
 
 import (

plugin/vmss_processor.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package plugin
 
 import (

plugin/vmss_processor_test.go

@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package plugin
 
 import (