Use buildcache or sccache for Windows CI jobs

[azeey]

Since windows CI jobs build all Gazebo dependencies from source, using a compiler caching tool like buildcache or sscache would greatly speed up CI jobs. We use ccache for Linux, but it doesn't seem like it's fully supported on Windows.

cc @mjcarroll

[mjcarroll]

I have had good luck with https://gitlab.com/bits-n-bites/buildcache, but it does require a slightly different set of flags for MSVC to get better caching behavior: gazebosim/gz-cmake#306