Photoshop: fix layer publish thumbnail missing in loader (#6061)

* OP-1645 - explicitly add thumbnail path to be integrated to Ayon

Thumbnail representation is set to 'delete', eg wont be integrated, another source of thumbnail must be used. This will effectively limit option of NOT pushing thumbnail to Ayon, which use case I am actuall not seeing.

* OP-1645 - added more description

* Remove comment

It works even for OP.

Co-authored-by: Jakub Trllo <43494761+iLLiCiTiT@users.noreply.github.com>

* Update openpype/plugins/publish/integrate_thumbnail_ayon.py

Co-authored-by: Jakub Trllo <43494761+iLLiCiTiT@users.noreply.github.com>

* Updates to docstring

Co-authored-by: Jakub Trllo <43494761+iLLiCiTiT@users.noreply.github.com>

* Update openpype/plugins/publish/integrate_thumbnail_ayon.py

Co-authored-by: Jakub Trllo <43494761+iLLiCiTiT@users.noreply.github.com>

* OP-1645 - fix formatting

---------

Co-authored-by: Jakub Trllo <43494761+iLLiCiTiT@users.noreply.github.com>

openpype/hosts/photoshop/plugins/publish/extract_review.py

@@ -224,6 +224,7 @@ class ExtractReview(publish.Extractor):
             "stagingDir": staging_dir,
             "tags": ["thumbnail", "delete"]
         })
+        instance.data["thumbnailPath"] = thumbnail_path
 
     def _check_and_resize(self, processed_img_names, source_files_pattern,
                           staging_dir):

openpype/plugins/publish/integrate_thumbnail_ayon.py

@@ -5,7 +5,21 @@
     pull into a scene.
 
     This one is used only as image describing content of published item and
-    shows up only in Loader in right column section.
+        shows up only in Loader or WebUI.
+
+    Instance must have 'published_representations' to
+        be able to integrate thumbnail.
+    Possible sources of thumbnail paths:
+    - instance.data["thumbnailPath"]
+    - representation with 'thumbnail' name in 'published_representations'
+    - context.data["thumbnailPath"]
+
+    Notes:
+        Issue with 'thumbnail' representation is that we most likely don't
+            want to integrate it as representation. Integrated representation
+            is polluting Loader and database without real usage. That's why
+            they usually have 'delete' tag to skip the integration.
+
 """
 
 import os