Add proper Zephyr module support with updated HAL for v3/v4 compatibility

[tbitcs]

Summary

This PR introduces first-class support for integrating CryptoAuthLib as a Zephyr module, compatible with Zephyr v3 and v4. It enables seamless integration into modern Zephyr-based applications using CMake and Kconfig, and updates the I2C and SPI HALs to align with Zephyr's evolving include path conventions.

Note: This change breaks compatibility with Zephyr v2.x due to header path and module resolution changes.

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Key Changes

• Added module.yml to enable Zephyr module recognition via west.
• Introduced ATCA_ZEPHYR_SUPPORT CMake option to toggle Zephyr build mode.
• Created zephyr_options.cmake to map CONFIG_ATCA_* Kconfig options to internal CMake flags.
• Refactored HAL sources (I2C, SPI) to use updated Zephyr include paths (zephyr/drivers/...) required in Zephyr ≥ v3.
• Updated top-level CMakeLists to:
• Detect Zephyr toolchain
• Build as a zephyr_library() when enabled
• Export include paths and config headers for Zephyr apps

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Integration Instructions

To include CryptoAuthLib as a Zephyr module:

Option 1: In-tree

Place CryptoAuthLib under modules/lib/cryptoauthlib and it will be automatically detected.

Option 2: Out-of-tree

If using a separate path:

# Add this line before find_package(Zephyr)
set(EXTRA_ZEPHYR_MODULES ${CMAKE_CURRENT_SOURCE_DIR}/../modules/lib/cryptoauthlib)

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Kconfig Support

Once integrated, you can configure CryptoAuthLib via prj.conf using new symbols:

CONFIG_ATCA_HAL_I2C=y
CONFIG_ATCA_CRYPTO_MBEDTLS=y
CONFIG_ATCA_DEVICE_SUPPORT_ECC608=y

These options automatically propagate to the CMake build system, enabling or disabling relevant sources and flags.

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Compatibility Notes

• Verified working on Zephyr v3.5 and v4.1.0
• Breaks backward compatibility with Zephyr v2.x
• No functional changes for non-Zephyr builds (Linux/MPLAB/Harmony remain unaffected)

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Request

If possible, please test against MPLAB Harmony and existing Linux builds to ensure continued compatibility. Feedback and improvements welcome!

Feature branch: https://github.com/BitConcepts/cryptoauthlib/tree/feature/zephyr-module-support-v3-v4