Kernel+Services: Introduce the DeviceMapper - a barebones hot-plug daemon handler

[supercomputer7]

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We already have AHCI support for hotplugging SATA devices. To be able to leverage this so far we needed to manually add a device node (or more than 1) in /dev. This is a preparation before USB HID could be added safely, as we will detect them in asynchronously way, so ideally WindowServer will get a notification about USB HID device being attached from SystemServer, based on this code in this PR, which will be enhanced to propagate notifications in a future PR :) Here's a discussion with @FireFox317 why this is necessary - https://discord.com/channels/830522505605283862/897113928168013855/1101937994828628109

Commit messages are still not written yet.

[supercomputer7]

The next-next PR to be in the queue, as I said before, is #12885.

[supercomputer7]

CI was red, so let's see if it's now green. Anyway, I wrote (about 2 weeks ago already) the commit messages, so reviews on this are appreciated as always!

[stale[bot]]

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