filter unstructured posts

[Mh-Asmi]

This pull request makes the following changes:

Test checklist:

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Fixes ushahidi/platform# .

Ping @ushahidi/platform

[linear]

USH-947 No one is able to see unstructured posts

How to reproduce

In a deployment that has Africa's Talking enabled (i.e. mzima-release).

1. From your command line, send a webhook request (mimicking Africa's Talking service) to have an unstructured post created as it came from SMS.

   curl -X 'POST' 'https://mzima-release-api.staging.ush.zone/sms/africas-talking' \
      -H 'connection: close' \
      -H 'content-type: application/x-www-form-urlencoded' -H 'user-agent: at-hydra-api/1.0' \
      -d $'linkId=f7a20132-41a4-462e-90c7-f6186b980211&text=Test+message+'$RANDOM'&to=22686&id=dc833ff8-eaf7-4f0d-9d79-22bdb2f27672&date=2023-10-26+08%3A59%3A38&from=%2B25401010101'
   

2. As an admin user in the deployment, see the list of posts, your test message should appear. If it doesn't, you have just reproduced the bug.

How it's not a problem with the SMS provider

1. In Africa's Talking data source configuration, enable 'Import to Survey'
2. Send the webhook request
3. Your post will most certainly appear in the list of posts now.

[webong]

This is good to go now!