feat: Ability to trigger campaigns via API

[sojan-official]

ref: https://discord.com/channels/647412545203994635/647729576427913228/943207330487615498

is there any way I could start a new campaign via an API interaction
I was planning to integrate with the instatus API to start a campaign that states the current status of the site

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The ability to trigger campaigns via API will open up more room for unique use cases.

Current limitations

• Campaigns will be triggered only if no conversation exists for the contact
• Campaigns trigger logic happens in frontend based on page rules in case of web widget channel

Thoughts

• The messages like site status or a product update note doesn't need to persist unless the user triggers a conversation over it.

ref: #3997 #2768

[sojan-official]

• the specific use case of sharing a downtime alert could be solved using one-off SMS campaigns which can be created via APIs

[brundles]

Looking forward to this. Do you have any ETA?

[pranavrajs]

I'm moving these to discussions as we will not be prioritizing these immediately.