Refactor syncWithPrimary and replicaTryPartialResynchronization

[nitaicaro]

In continuation to #945

syncWithPrimary:

• Refactored all labels, frees and error handling to function syncWithPrimaryHandleNoResponseError
• Refactored repl_state state machine from if-else format to switch-case format
• Besides changing the repl_state, all state machine logic moved to helper functions

replicaTryPartialResynchronization:
This function was performing two different jobs based on the value of the read_reply argument -

• read_reply == 0: Sends the PSYNC command to the primary server.
• read_reply == 1: Reads and processes the reply to the PSYNC command.

This change simplifies the logic by clearly separating the writing and reading stages of the PSYNC process.

The PR was split into individual commits for easy review.

[codecov]

Codecov Report

Attention: Patch coverage is 73.07692% with 49 lines in your changes missing coverage. Please review.

Project coverage is 70.97%. Comparing base (3032ccd) to head (447740b).

Files with missing lines	Patch %	Lines
src/replication.c	73.07%	49 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #1476      +/-   ##
============================================
+ Coverage     70.81%   70.97%   +0.16%     
============================================
  Files           121      121              
  Lines         65132    65173      +41     
============================================
+ Hits          46121    46258     +137     
+ Misses        19011    18915      -96     

Files with missing lines	Coverage Δ
src/replication.c	87.09% <73.07%> (-0.41%)	⬇️

... and 15 files with indirect coverage changes

[PingXie]

This kind of refactoring is really valuable for the long-term health of Valkey. It makes the codebase easier to understand, maintain, and improve, which ultimately helps us deliver better features faster. Thanks @nitaicaro and @naglera!

My main focus in this review is on the high level code structure, which looks great to me. That said, the use of goto in syncWithPrimary stands out. Let's aim to eliminate all goto statements from that function. I'll take another look and provide more detailed feedback once that's addressed.