Added helper functions for creating various Tcp packets

[compscidr]

Adds a factory class for creating various Tcp packets:

• ACK
• FIN
• RST
• SYN
• SYN-ACK

Also adds test coverage to ensure they all work.

Fixes: #30

[codecov]

Codecov Report

Attention: Patch coverage is 96.82540% with 4 lines in your changes missing coverage. Please review.

Project coverage is 97.89%. Comparing base (ab3e8cf) to head (1a8fbb2).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
.../jasonernst/knet/transport/tcp/TcpHeaderFactory.kt	96.63%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #32      +/-   ##
============================================
- Coverage     97.97%   97.89%   -0.09%     
- Complexity      385      400      +15     
============================================
  Files            55       56       +1     
  Lines          1827     1947     +120     
  Branches        208      213       +5     
============================================
+ Hits           1790     1906     +116     
- Misses           30       32       +2     
- Partials          7        9       +2     

Flag	Coverage Δ
unittests	97.89% <96.82%> (-0.09%)	⬇️

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