feat(nestjs): Derive SentryCron monitor config from @Cron

[wedamija]

Description

@SentryCron now sends the schedule and time zone of the method's @Cron() decorator with its check-ins, so Sentry creates the monitor on the first run:

@Cron('0 30 9 * * 1-5', { timeZone: 'Europe/Vienna' })
@SentryCron('daily-report', { checkinMargin: 2 })
async dailyReport() {}

This is on by default; pass fromCronDecorator: false to send no config. Schedules Sentry would read differently from how @nestjs/schedule runs them (sub-minute, numeric months, some day-field combinations, fixed UTC offsets) send no config, because a wrong schedule causes false missed check-in alerts. Without a timeZone, the server's local time zone is sent. A config with an explicit schedule is used as is. Monitors created this way are billed, and the schedule and time zone are overwritten from @Cron() on each check-in.

Motivation

Check-ins for monitors that don't exist are dropped, so users have to create each monitor by hand, even though the schedule is already in their code.

Testing

Unit tests for the conversion and decorator order, plus an e2e test in nestjs-basic that checks the config sent with the check-in.

Docs: getsentry/sentry-docs#19782

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