feat: add validate hello method

[shoothzj]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 12 lines in your changes missing coverage. Please review.

Project coverage is 33.46%. Comparing base (c21236d) to head (346b675).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opcua/conn.go	20.00%	8 Missing ⚠️
opcua/secure_channel.go	50.00%	2 Missing and 1 partial ⚠️
opcua/server.go	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
+ Coverage   33.06%   33.46%   +0.40%     
==========================================
  Files          28       30       +2     
  Lines        1742     1760      +18     
==========================================
+ Hits          576      589      +13     
- Misses       1008     1014       +6     
+ Partials      158      157       -1     

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