Release v2.4.0

Changed

• Use Golioth Firmware SDK v0.15.0
• Update board names for Zephyr hardware model v2
• Use zephyr-network-info v1.2.1
• Update board names for hardware model v2
• Use socs folder for chip-specific configuration
• Remove application-specific WiFi manager and use the one in Golioth common library
• Pare down manifest allow-list to remove unused packages
• Add GitHub actions workflows for build and release