Signature validation function for Webhook manager

[jstinsonCCHMC]

Is your feature request related to a problem? Please describe.

In the previous Box Python SDK, the Webhooks object had a function "validate_message" which validated a box webhook payload given your signature keys. This is missing in the new Webhook manager.

Describe the solution you'd like

Add this helper function to the Webhook manager

Describe alternatives you've considered

Easy to do manually, but it is described in current box documentation as "provided for your convenience in the official Box SDKs".

[mwwoda]

Hi @jstinsonCCHMC
Thank you for raising this issue. Signature validation is indeed on our roadmap, but I can't give an exact timeframe for when it's coming to the SDK. I will forward this to the team so that we can prioritize it.