Expose image api for other clients as api v1.4

[newhinton]

This allows external apps to resolve images.

Could someone please test the api-endpoints? They have been very unreliable for me, though i dont know why. The actual code behind the endpoint works, and is identical to the internal api.

[cheywood]

As a consumer of the API we're looking forward to this MR for #826 👍

[Pauldb8]

We're looking forward to this merge to for the support to Iotas application for seeing / adding pictures. Thank you very much !

[enjeck]

Doesn't seem to work for me, but it might be that I'm not using the API right. I make a request and get no response:

curl -u admin:admin \
  "http://nextcloud.local/apps/notes/api/v1.4/attachment/135?path=img.png"

Nothing from using the image folder either:

curl -u admin:admin \
  "http://nextcloud.local/apps/notes/api/v1.4/attachment/135?path=.attachments.135/img.png"

Using other versions of API instead of v1.4 doesn't work either. But I confirmed note does exist with attachment:

curl -u admin:admin \
  "http://nextcloud.local/apps/notes/api/v1/notes/135"                                       
{"id":135,"title":"New note","modified":1745697329,"category":"test","favorite":false,"readonly":false,"internalPath":"\/Notes\/test\/New note.md","shareTypes":[],"isShared":false,"error":false,"errorType":"","content":"test\n\n![img.png](.attachments.135\/img.png)","etag":"56029a81f877364a391d6c686f3351d0"}%