Sentry Cron monitoring support

[lacolaco]

https://docs.sentry.io/platforms/node/crons/

Sentry will support cron monitoring. It is good to use with the cf scheduled trigger. I hope toucan-js will integrate with it.

[timfish]

I'm guessing parts of this will need to be copied form the node client:
https://github.com/getsentry/sentry-javascript/blob/5fdaaa7234804fecaa25803ced39f601c6175cf4/packages/node/src/client.ts#L166

[timfish]

I'm in the process of moving check-in support to a shared client in @sentry/core, currently named ServerRuntimeClient.

After this is released, the toucan client should be able to extend that rather than the BaseClient and this will add support for check-ins/cron monitoring.