ci: improve caching for faster builds

[briaguya-ai]

ios

getting ccache working with xcode seems to not be super straightforward, and most of the build time looks to have been from dependencies, so i just added a simple cache for the build-cmake directory

windows

following the pattern from soh i updated windows to

• use simple cache for the build-cmake directory
• use simple cache for the vcpkg directory
• use sccache for the build

summary

this gets build times to a point where they aren't incredibly painful, we can look into more optimization later