Always return 200 for OPTS UTF8 or OPTS UTF-8 ON

[amirzak]

Fix #266 and #531. Took inspiration from vsftpd for 200 reply message - https://github.com/dagwieers/vsftpd/blob/ce2fa4288b92683f832c3b5179d5cb2a77d0750e/opts.c#L20

Let me know if additional changes are needed in order to merge it.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 69.72%. Comparing base (4165a47) to head (f3abf96). Report is 57 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #596      +/-   ##
==========================================
- Coverage   69.81%   69.72%   -0.10%     
==========================================
  Files           9        9              
  Lines        3614     3623       +9     
==========================================
+ Hits         2523     2526       +3     
- Misses       1091     1097       +6     

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