Use :: to force top-level constant resolution

MSP-11152

When `Msf::DBManager::Import::MetasploitFramework` is included in
`Msf::DBManager::Import`, it's child namespace of
`Msf::DBManager::Import::MetasploitFramework::Zip becomes resolvable as
`Zip` in `Msf::DBManager::Import` methods, so need to use `::Zip` to
cause `Zip` to be resolved from rubyzip gem.

Author: limhoff-r7

lib/msf/core/db_manager/import.rb

@@ -115,7 +115,10 @@ def import_file(args={}, &block)
     else
       case data[0,4]
       when "PK\x03\x04"
-        data = Zip::File.open(filename)
+        # When Msf::DBManager::Import::MetasploitFramework is included, it's child namespace of
+        # Msf::DBManager::Import::MetasploitFramework::Zip becomes resolvable as Zip here, so need to use ::Zip so Zip
+        # is resolved as one from rubyzip gem.
+        data = ::Zip::File.open(filename)
       when "\xd4\xc3\xb2\xa1", "\xa1\xb2\xc3\xd4"
         data = PacketFu::PcapFile.new(:filename => filename)
       else
@@ -174,8 +177,10 @@ def import_file(args={}, &block)
   #
   # @raise [Msf::DBImportError] if the type can't be detected
   def import_filetype_detect(data)
-
-    if data and data.kind_of? Zip::File
+    # When Msf::DBManager::Import::MetasploitFramework is included, it's child namespace of
+    # Msf::DBManager::Import::MetasploitFramework::Zip becomes resolvable as Zip here, so need to use ::Zip so Zip
+    # is resolved as one from rubyzip gem.
+    if data and data.kind_of? ::Zip::File
       if data.entries.empty?
         raise Msf::DBImportError.new("The zip file provided is empty.")
       end