Take control over maybenot dependencies and verification

[faern]

This PR is a sibling-PR to mullvad/wireguard-go#22.

This switches to a version of the wireguard-go submodule where maybenot-ffi is not included and built as a submodule. Instead there is a local crate in wireguard-go that acts as a simple wrapper around maybenot-ffi, with helper files to build it for static linking. This allows us to include the wrapper (and transitively all its dependencies) in our main workspace and track all dependency versions and checksums here. This simplifies dependency management, reproducible builds and supply chain security checks.

This PR is going to be colliding a bit with DAITA v2 for Windows (#7457), we have to discuss which one to get merged first.

Fixes DES-1360 and DES-1645

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This change is 

[linear]

DES-1360 Improve `maybenot.h` inconsistent build behavior

DES-1645 Take control over `maybenot` dependencies and verification

[dlon]

I like it. Solves the lockfile situation and makes static vs dynamic linking less messy. 👍

Reviewed 8 of 9 files at r1.
Reviewable status: 8 of 10 files reviewed, all discussions resolved

[albin-mullvad]

Reviewed 4 of 9 files at r1.
Reviewable status: 8 of 10 files reviewed, all discussions resolved

[kl]

Reviewed 8 of 9 files at r1, 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[MarkusPettersson98]

There are still some references to git submodule update --init --recursive --depth=1 wireguard-go-rs (for example in the top-level README.md). We should no longer need to checkout recursive submodules in wireguard-go-rs 😊

Reviewed 8 of 9 files at r1, 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[albin-mullvad]

Do we need to pass --locked to the cargo build command in the maybenot-ffi Makefile since we currently don't seem to do so? Or somehow address it in another way?

https://github.com/maybenot-io/maybenot/blob/5f1389fd81523bb686f3054c460e4365e10527db/crates/maybenot-ffi/Makefile#L32

EDIT: Sorry, never mind, seems to be handled in the related wireguard-go PR.