[4.0] Figure out the image size for external adapters

[dgrammatiko]

Pull Request is supplamentary to #33724

Summary of Changes

Testing Instructions

Actual result BEFORE applying this Pull Request

Expected result AFTER applying this Pull Request

Documentation Changes Required

[richard67]

I have tested this item ✅ successfully on 5252057

I've tested with success as follows:

1. Applied the patch from PR [4.0] Support External Adapters For Media Form Field #33724 and installed the dropbox plugin as described there in testing instructions.
2. Removed the guzzlehttp folder from the plugin's vendor folder as described here, so that the one shipped with the CMS is used, to work around the issue linked in that comment, too: [4.0] Support External Adapters For Media Form Field #33724 (comment) .
3. Inserted an image into an article, using an image from the Dropbox.
   Result: See [4.0] Support External Adapters For Media Form Field #33724 (comment) .
4. Applied the patch of this PR.
5. Repeated step 3 a few times with different images:
   Result: Image is visible, and the tag has the height and width attributes equal to height and width of the image.

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   _{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/34177.}

[richard67]

@chmst Could you test this PR as desribed in my test result above?

It's the same test you already have done for @joomdonation 's PR with the external Dropbox adapter.

First check if it has your issue, then apply the patch of this PR here, too, run npm ci and check again.

For me it worked.

[chmst]

I have tested this item ✅ successfully on 5252057

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/34177.}

[richard67]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/34177.}

[dgrammatiko]

Please DO NOT merge this BEFORE #33724

[richard67]

@dgrammatiko The other PR has been merged now. Could you solve here the conflict resulting from that?

[richard67]

Previous tests and RTC are still valid since the one commit after the tests was a clean branch update. In addition I have repeated my test with the same result as before, success.