Kernel/riscv64: Get the memory map from the FDT and dump it

[Hendiadyoin1]

LibDeviceTree: Make the dump more akin to the original fdtdump

This also makes it possible to compile the library in the Kernel

Meta: Compile fdtdump on lagom

Kernel/riscv64: Take the memory map from the FDT and dump it

For this the BootInfo struct was made architecture specific

Kernel/riscv64: Initialize PCI controllers with the help of the FDT

Currently the search path is limited to /soc/ but this is enough to get it to work on qemu.

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depends on #22924 ~~and (not actually) on #22923~~

[ADKaster]

Conflicts with the hacky multiboot memory map, and some comments to address :)

[spholz]

You don't seem to use validate_flattened_device_tree anywhere. Verifying that the FDT is valid might be a good idea. It looks like you should be able to use that function in init before MemoryManager init.

We sadly can't use that function in pre_init, as it uses warnln everywhere. Maybe at least verify the magic bytes before copying the fdt based on its totalsize?