fix: persist message with already cached file

[Rohit3523]

Proposed changes

When we send the same images in different messages, only the image in the first message will open in the preview, not the ones in the rest. For example, if we send images one and two across three messages, we can tap and open the preview for the image in the first message, but not for the images in the second and third messages. If we send only one image multiple times, this issue occurs too

Issue(s)

N/A

How to test or reproduce

URL: https://********.rocket.chat/api/v1/chat.postMessage
Method: POST
Header: {
     'X-Auth-Token': '**********',
     'X-User-Id': '**********'
}
body: {
  "roomId": "",
  "attachments": [
    {
      "image_url": "https://i.pinimg.com/474x/c4/23/63/c423639b72feb5c93a14144fb50008c3.jpg" //or any random image url
    }
  ]
}

Screenshots

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Further comments

N/A