ci: Check binaries separately from building them

[mathbunnyru]

High Level Overview of Change

This would allow decoupling building binaries from testing them.
We're not there yet, but this is a step that should help.

Context of Change

API Impact

• Public API: New feature (new methods and/or new fields)
• Public API: Breaking change (in general, breaking changes should only impact the next api_version)
• libxrpl change (any change that may affect libxrpl or dependents of libxrpl)
• Peer protocol change (must be backward compatible or bump the peer protocol version)