Ensure require of metasploit/credential/engine is optional

Author: mbuck-r7

lib/metasploit/framework/common_engine.rb

@@ -9,9 +9,9 @@
 #
 
 require 'metasploit/model/engine'
-require 'metasploit/credential/engine'
 require 'metasploit/concern/engine'
 require 'metasploit_data_models/engine'
+Metasploit::Framework::Require.optionally_require_metasploit_credential_engine
 
 # `Rails::Engine` behavior common to both {Metasploit::Framework::Application} and {Metasploit::Framework::Engine}.
 module Metasploit::Framework::CommonEngine

lib/metasploit/framework/require.rb

@@ -72,6 +72,19 @@ def self.optionally_include_metasploit_credential_creation(including_module)
         end
       end
 
+      # Tries to `require 'metasploit/credential/engine'`.
+      #
+      # @example
+      #   Metasploit::Framework::Require.optionally_require_metasploit_credential_engine
+      #
+      # @return [void]
+      def self.optionally_require_metasploit_credential_engine
+        optionally(
+          'metasploit/credential/engine',
+          "metasploit-credential not in the bundle",
+        )
+      end
+
       #
       # Instance Methods
       #