meson: Install Cargo-generated lib directly

[obiwac]

Currently, when building with Meson, an archive is created containing the archive generated by Cargo (so not directly the object files contained withing the Cargo-generated archive). This causes issues when linking and required an explicit ranlib or ar -s step to be issued before the library is usable:

ld: archive member 'libwgpu_native.a' not a mach-o file in '.../libwgpu_native.a'

It doesn't look like static_library really supports this kind of usecase.

This PR simply installs the static library artifact generated by Cargo directly instead. Unfortunately I don't think there's an elegant way to pass a meson library object to pkg.generate in this situation, so I've just set libraries manually (since it allows arbitrary strings). I'm by no means a Meson expert so do let me know if there's a better way that I'm overlooking :)

@KentaTheBugMaker pinging you as the original author of meson.build (#84) for your input.

[almarklein]

This looks fine by me, but @KentaTheBugMaker understand this code way better.