[Components] mailrelay

# mailrelay
## URLs
- https://apidocs.mailrelay.com/#overview
## Webhook Sources
### new-subscriber-instant
#### Description
Emit new event when a new subscriber is added to a list. Requires selecting a specific subscriber list.
### new-email-open-instant
#### Description
Emit new event when a subscriber opens an email campaign. Requires specifying the campaign to monitor for opens.
### new-click-instant
#### Description
Emit new event when a link in a campaign email is clicked. Requires selecting a campaign to monitor.
## Actions
### create-subscriber
#### Description
Add a new subscriber to a list. Requires subscriber email and target list. Optional props include name and custom fields.
### create-campaign
#### Description
Create a new email campaign. Requires subject, sender information, and email content. Optional props include segmentation rules and scheduling.
### send-campaign
#### Description
Send a draft campaign to selected recipients. Requires campaign ID and recipient list or segment.