Add support for CH32H417

[So1aric]

CH32H417 is a heterogeneous dual-core RISC-V MCU from WCH (Nanjing Qinheng Microelectronics), featuring one QingKe V3F core and one QingKe V5F core. I'm opening a separate issue rather than commenting on the tracking issue because this heterogeneity raises questions beyond a typical single-core port.
MicroZig already supports the CH32V family, but the official MountRiver Studio workflow for the CH32H417 is quite different: you write two separate firmware binaries, one for each core, and then merge them into a single .bin file that can be flashed to the chip. I'm not sure how MicroZig should organize this kind of multi-core project — that is, how the two cores' firmware should be structured.
I recently bought a nanoCH32H417 board and would be happy to contribute the port.

[mattnite]

I feel like the right way to do this is to expose it in the port some way. There are already different ways that ports will customize artifact generation. IIRC LPC needs to patch ELF with a checksum, and I think there are some image generation scripts for ESP.

This could work largely the same. I'm not sure though if the method is specific to their bootloader, or it's lower level. Regardless, this is quite possible and can be done in a way to make tooling reusable.