Feat/client server

[YugenUniverse]

Purpose

The goal of this pull request is to enable concurrent access to GPS data by implementing a TCP Server/Client architecture within gpslib, resolving #2.
This PR decouples the hardware connection from the data processing, allowing a single Server instance to broadcast raw GPS data to multiple Clients simultaneously.

Overview

This pull request introduces significant changes to gps_interface to support connection management and ensure data integrity for both NMEA and UBX protocols.

• Added TCP Server/Client Modes: Implemented the two new modes and their respective interface openers. Extended gps_serial_port with a server context that wraps the underlying physical GPS port, managing the server socket in the top layer and the serial connection in the bottom layer.
• Packet Reconstruction: Modified gps_interface_get_line to reconstruct the full raw packet (re-attaching stripped Start Sequences/Sync Bytes and Newlines) before broadcasting. This ensures clients receive valid, checksum-verifiable data.
• Error Handling: Implemented a fail-count mechanism in broadcast_to_clients. It uses MSG_NOSIGNAL to detect broken pipes (EPIPE/ECONNRESET) and disconnects dead clients immediately, while tolerating temporary failures (up to MAX_FAILS) for congested connections.
• Thread Safety: Added pthread support to manage the acceptance of new connections and mutexes to protect the client socket and failure lists during broadcast operations.

Guidance

I recommend reviewing the files in the following order:

1. gps_interface.h: Start here to review the changes to the gps_serial_port struct and the new server context definitions.
2. gps_interface.c:
   • SERVER Logic:
     1. Review gps_interface_open_server to see how the context is initialized.
     2. Review gps_interface_read and gps_interface_get_line to see how the code detects the protocol type and reconstructs the full message buffer before calling broadcast.
     3. Review broadcast_to_clients to examine the MSG_NOSIGNAL implementation and the strike-count logic for handling client disconnects.
     4. Review acceptThreadFunc, the detached thread that continuously listens for and accepts new client connections.
   • CLIENT Logic:
     1. Review gps_interface_open_client to see how the connection is established.
     2. Review gps_interface_read for the client-side socket handling.

[KevinRomanello]

good job 👍🏿😎🎾