Refactor syncWithPrimary and replicaTryPartialResynchronization (#1476)

In continuation to #945

**syncWithPrimary:**
- Refactored all error handling to function `syncWithPrimaryHandleError`
- 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.

Signed-off-by: Nitai Caro <caronita@amazon.com>
Co-authored-by: Nitai Caro <caronita@amazon.com>

Author: nitaicaro