Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
All your needs are in the STM32 Cube Firmware packages
For example, If you are using STM32F4 you need to download STM32CubeF4 from ST website and look for I2C examples within the downloaded archive.