Stop agent execution when it is not registered

[TomasTurina]

Related issue
#359

Description

This PR prevents an agent from continuing to run indefinitely in the following scenarios:

• The agent has not been previously registered.
• The server does not recognize the agent during authentication.
• The agent key used to authenticate is invalid.

Logs/Alerts example

###Agent not registered:

# ./wazuh-agent --run --config-file wazuh-agent.yml 
[2024-12-02 19:33:11.138] [wazuh-agent] [info] [INFO] [process_options_unix.cpp:24] [StartAgent] Starting wazuh-agent
[2024-12-02 19:33:11.168] [wazuh-agent] [info] [INFO] [communicator.hpp:55] [Communicator] Using insecure connection.
[2024-12-02 19:33:11.169] [wazuh-agent] [critical] [CRITICAL] [main.cpp:98] [main] An error occurred: The agent is not registered.

Agent not exists error (API):

# ./wazuh-agent --run --config-file wazuh-agent.yml 
[2024-12-02 19:34:46.700] [wazuh-agent] [info] [INFO] [process_options_unix.cpp:24] [StartAgent] Starting wazuh-agent
[2024-12-02 19:34:46.706] [wazuh-agent] [info] [INFO] [communicator.hpp:55] [Communicator] Using insecure connection.
[2024-12-02 19:34:46.712] [wazuh-agent] [critical] [CRITICAL] [main.cpp:98] [main] An error occurred: Agent does not exist.

Agent key invalid error (API):

# ./wazuh-agent --run --config-file wazuh-agent.yml 
[2024-12-02 19:35:31.394] [wazuh-agent] [info] [INFO] [process_options_unix.cpp:24] [StartAgent] Starting wazuh-agent
[2024-12-02 19:35:31.397] [wazuh-agent] [info] [INFO] [communicator.hpp:55] [Communicator] Using insecure connection.
[2024-12-02 19:35:31.402] [wazuh-agent] [critical] [CRITICAL] [main.cpp:98] [main] An error occurred: Invalid key.

Tests

• Compilation without warnings in every supported platform
  • Linux
  • Windows
  • MAC OS X

[jr0me]

we won't throw if the response code is unauthorized or forbidden and if the message does not match. Would that be OK? because this looks like it is very coupled to the specific string we will find in the message.

[TomasTurina]

These are the messages that the server uses to indicate that the agent has not been recognized. Since this cannot be guessed by just analyzing the error code, we need to verify the message. cc @wazuh/devel-pyserver