main/depthcharge-tools: new aport

From readme on github which describes what is it:

This project is a collection of tools that ease and automate interacting with depthcharge, the Chrome OS bootloader.

Depthcharge is built into the firmware of Chrome OS boards, uses a custom verified boot flow and usually cannot boot other operating systems as is. This means someone who wants to use e.g. Debian on these boards need to either replace the firmware or work their system into the format depthcharge expects. These tools are about the latter.

I found that it's the most convenient way to generate kernel + dtb + initramfs image for Chrome OS devices.

It can be done in kernel packages like Alpine does (e.g. https://gitlab.alpinelinux.org/alpine/aports/-/blob/master/testing/linux-gru/APKBUILD#L157-179), but we need initramfs (at least for FDE), therefore we need to do that each time when generating initramfs.

I want to integrate it with boot-deploy (like generating boot.img's) and will send corresponding MR there when this one is merged