ELF scatter-loading fixes and TC3xx support

[bigbrett]

Major modifications to flash elf loading to properly support external flash and TC3xx.

• Modifies elf scatter loading and hash checking to fully support external flash (buffered reading)
• Updates AURIX HAL erase to support arbitrary (non-sector size/aligned) erases
• ELF file preprocessing via new tool: squashelf
• ELF loading added to AURIX TC3xx HAL and demos, including wbaurixtool.sh
• Doc updates

Other:

• Adds DEBUG_UART support for AURIX TC3xx
• Fixes AURIX doc issues LED2 is not blinking , but LED 1 blinking. #564 and wolfboot with wolfHSM - NVM tool #565
• Updates test app linker scripts to force partition alignment to sector size

[Copilot]

Pull Request Overview

This PR introduces support for ELF scatter-loading on external flash and integrates TC3xx support into the wolfBoot bootloader, while also adding DEBUG_UART functionality and updating related documentation.

• Refactors preprocessor macros for flash scatter-loading and adjusts flash writing logic in the TC3xx HAL.
• Adds buffered flash write and erase improvements along with DEBUG_UART support, including UART initialization and transmission.
• Updates firmware update and IDE documentation to reflect new ELF loading procedures and configuration changes.

Reviewed Changes

Copilot reviewed 26 out of 42 changed files in this pull request and generated no comments.

File	Description
hal/sim.c	Renamed the preprocessor macro from WOLFBOOT_ELF_SCATTERED to WOLFBOOT_ELF_FLASH_SCATTER.
hal/aurix_tc3xx.c	Enhances flash write logic with sector-based buffering and adds DEBUG_UART support functions.
docs/firmware_update.md	Expands documentation on ELF loading, including RAM and flash approaches and dual-layer verification.
IDE/AURIX/README.md	Updates build instructions and usage notes to support both standard and ELF file-based images.

Files not reviewed (16)

• IDE/AURIX/test-app-wolfHSM/.cproject: Language not supported
• IDE/AURIX/test-app-wolfHSM/Lcf_Gnuc_Tricore_Tc.lsl.in: Language not supported
• IDE/AURIX/test-app/.cproject: Language not supported
• IDE/AURIX/test-app/.settings/language.settings.xml: Language not supported
• IDE/AURIX/test-app/Lcf_Gnuc_Tricore_Tc.lsl.in: Language not supported
• IDE/AURIX/wolfBoot-tc3xx-wolfHSM/.cproject: Language not supported
• IDE/AURIX/wolfBoot-tc3xx-wolfHSM/Lcf_Gnuc_Tricore_Tc.lsl: Language not supported
• IDE/AURIX/wolfBoot-tc3xx-wolfHSM/wolfBoot_macros.in: Language not supported
• IDE/AURIX/wolfBoot-tc3xx/.cproject: Language not supported
• IDE/AURIX/wolfBoot-tc3xx/.settings/language.settings.xml: Language not supported
• IDE/AURIX/wolfBoot-tc3xx/Lcf_Gnuc_Tricore_Tc.lsl: Language not supported
• IDE/AURIX/wolfBoot-tc3xx/wolfBoot_macros.in: Language not supported
• Makefile: Language not supported
• arch.mk: Language not supported
• config/examples/sim-elf-scattered.config: Language not supported
• config/examples/sim32-elf-scattered.config: Language not supported

[danielinux]

Refactor of the elf scattering OK, as discussed. Both the feature and the squashelf tools are well documented. Squashelf tool compiles and works fine.

Did not review the TC3xx specific code / IDE / debugging scripts

[danielinux]

@bigbrett please rebase to latest master to resolve conflicts, then assign to @billphipps for a final review on HW-specific components.

[billphipps]

LGTM! Minor comments and I didn't get a chance to test it out locally. Consider some tests for squashelf?

[billphipps]

Looks good to me!

[bigbrett]

@dgarske this has been approved by both @danielinux and @billphipps , if you could pls do the honors...