dumpling should fail when provided positional parameters to CLI

[glkappe]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do? If possible, provide a recipe for reproducing the error.
   https://asktug.com/t/topic/67342
   

And no detailed execution statements are output in debug mode
debug_test.log

2. What did you expect to see?
   All exported data

3. What did you see instead?
   Report an error

4. Versions of the cluster

   • Dumpling version (run dumpling -V):

     (paste Dumpling version here)
     

   • Source database version (execute SELECT version(); in a MySQL client):

     (paste source database version here)
     

   • Other interesting information (system version, hardware config, etc):

5. Operation logs

   • Please upload dumpling.log for Dumpling if possible
   • Other interesting logs

6. Configuration of the cluster and the task

   • running command for Dumpling if possible

[kennytm]

What to do: Basically throw an error in main.go if pflag.NArg() is not 0.