Refactor AUTH and HELLO implementation to abstract away all the business logic

[danielealbano]

This PR reorganise the AUTH and HELLO command to abstract away into helpers all the business logic.

[codecov]

Codecov Report

Patch coverage: 83.64% and project coverage change: -0.01 ⚠️

Comparison is base (d9c82ae) 78.27% compared to head (149627b) 78.26%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #397      +/-   ##
==========================================
- Coverage   78.27%   78.26%   -0.01%     
==========================================
  Files         192      193       +1     
  Lines       13203    13231      +28     
==========================================
+ Hits        10334    10354      +20     
- Misses       2869     2877       +8     

Flag	Coverage Δ
unittests	78.26% <83.64%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
...c/module/redis/command/module_redis_command_auth.c	100.00% <ø> (ø)
...ommand/helpers/module_redis_command_helper_hello.c	80.22% <80.22%> (ø)
...command/helpers/module_redis_command_helper_auth.c	88.89% <100.00%> (+1.79%)	⬆️
.../module/redis/command/module_redis_command_hello.c	100.00% <100.00%> (+21.95%)	⬆️

... and 2 files with indirect coverage changes

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