Option to disable SMPTE Rate Check

As the industry moves towards faster and faster rates for various media (headsets, immersive material). We're seeing content rise above the 60fps ceiling, for better or worse, that the SMPTE is currently limiting us to. Because of this, our editorial workflow is hampered by the fact that we get an error while trying to convert/conform 90fps material.

https://github.com/AcademySoftwareFoundation/OpenTimelineIO/blob/ad449d8122e778e80e57ac7e6b1b1a38afe7f91b/src/opentime/rationalTime.cpp#L326

We've written around this problem with custom TimeCode objects, but I'm wondering if it will be a strict policy forever and we should wait for SMPTE to update their standards, or if there's wiggle room for opt-in/out of the explicit rate checking. RationalTime supports any rate, so I would like to assume timecode could as well, even if there's a toggle or optional preference for how strict it should be.

Start with src/opentime/rationalTime.cpp at the linked rate-checking code, then review how RationalTime and custom TimeCode objects handle rates. Determine how an opt-in or opt-out policy could support 90fps while preserving strict checking, and verify that conversion/conform workflows behave accordingly.

Written by the indexing model from the issue text.