DAP: launch should be localfs == true

`launch` invokes a debuggee process on the same file system so
we can assume `localfs == true`.

fix ruby/vscode-rdbg#82

Author: ko1

lib/debug/server_dap.rb

@@ -279,7 +279,8 @@ def process
         ## boot/configuration
         when 'launch'
           send_response req
-          UI_DAP.local_fs_map_set req.dig('arguments', 'localfs') || req.dig('arguments', 'localfsMap')
+          # `launch` runs on debuggee on the same file system
+          UI_DAP.local_fs_map_set req.dig('arguments', 'localfs') || req.dig('arguments', 'localfsMap') || true
           @nonstop = true
 
         when 'attach'