Support glob for `include` spec paths

At my company we've recently moved our project to use per-framework-defined spec files as we'd like to define these within the frameworks themselves and their definitions be independent of the rest of the project (excluding dependencies of course). The reasoning for this is that we find this approach to be more manageable for a large, modularized-project where it can currently become tricky to find where a framework definition may be placed.

To my knowledge it seems you can not use glob style paths in the include: directive. As a workaround we've created a script that finds the paths for these subspecs and generates/includes each of them. While this works (albeit with a few headaches due to relative/absolute paths not working as I'd expect with nested include: calls), it'd be really nice if there was first-party support for glob style include: paths.

Start by tracing how the include: directive resolves paths, including the nested include: behavior described in the issue. Done means glob-style include paths are supported with predictable relative and absolute path handling, including for nested includes; no specific files or tests are named.