Add support for building Cargo-C recipes for native builds
WIP till phase 1 items are complete.
Will probably want some image updates for the bootstrap phase...
Steps to test:
./cerbero-uninstalled -v rust fetch-bootstrap
./cerbero-uninstalled -v rust bootstrap --offline
./cerbero-uninstalled -v rust fetch-package gstreamer-1.0
./cerbero-uninstalled -v rust package gstreamer-1.0 --offline -t
Enabled by default for macOS, MSVC, Linux (without static plugins). Does work on iOS and Android, but static libs are too huge, so not enabled by default for now.