Validate connection API

**Describe the idea**
Right now, the only way to validate that things are well-configured is to do a capture_message call (per your docs) and then go look at the Sentry UI.

It would be very helpful to have an api like `Sentry.validate_configuration` that checked the settings locally and then actually phoned-home as well to make sure that the DSN and such were good.

**Why do you think it's beneficial to most of the users**
This would let one programatically confirm all was well. It would be very helpful in a diagnostics page in the app (important thing we have and care about) but also things like Helm chart tests.

**Possible implementation**
You could just do a capture_message internally but just wrap it in something blocking that confirms the transmission actually happened successfully. That would almost be ideal as it is the "real" codepath. Then on the back-end, you could filter those messages out, or even just default them to Ignored.

Comienza con la documentación que describe capture_message, ya que el issue lo identifica como la ruta de validación actual. Sigue cómo se transmite una captura y determina el comportamiento esperado de validación local y de phone-home. Se considera terminado cuando una API puede informar si la configuración y la transmisión tuvieron éxito, con un resultado utilizable para las páginas de diagnóstico y las pruebas del Helm chart.

Escrito por el modelo de indexación a partir del texto del issue.