Viaduct

[Viaduct](https://github.com/mo zilla/application-services/blob/main/components/viaduct/README.md) initialization is required for all platforms and for multiple components.

There are 3 different options to use viaduct:

• Any libxul based can ignore initialization, since it's handled by libxul.
• Using the reqwest backend, which uses the reqwest library and a reqwest-managed thread.
• Implementing the C FFI like libxul does (https://searchfox.org/mozilla-central/source/toolkit/components/viaduct).