Uploading an image while file upload is disabled

Description:

We disabled all file uploads for our rocket chat instance. This works for "normal" file uploads. But if a user copies and pastes an image into the text box of a chat window, the dialog to upload a file is displayed. When file uploads are disabled, this dialog shouldn't even be displayed.

When the user tries to upload the image, the upload will be correctly blocked. But the displayed error message can't be customized/translated.

Steps to reproduce:

1. Disable all fileuploads in rocket-chat administration
2. Copy and paste an image in the textbox of a chat window
3. Try to send the image

Expected behavior:

The dialog to upload the image shouldn't even be displayed.

Alternatively the error message for the rejected file upload should be customizable via translation files.

Actual behavior:

The dialog to upload an image is displayed. The upload will be blocked but the resulting error message can't be customized/translated.

Server Setup Information:

• Version of Rocket.Chat Server: 3.15.0

Reproduce the issue by disabling file uploads, then pasting an image into a chat textbox and attempting to send it. Trace the frontend path from the paste event to the upload dialog and the file-upload setting; done means the dialog is suppressed when uploads are disabled, or the rejected-upload message is available through translations.