SiteSync: implemented in Ayon Loader (#5962)

* Added new SiteSync model

Used to get information from SiteSync module to enhance Loader UI.

* Added new SiteSync method to controller

Other models will be using these to get information pertaining SiteSync

* Added missed commit

* Implemented collection of SiteSync info

* Added AvailabilityDelegate

Shows how many representations are present locally and remotely in Loader summary page.

* Added fields to store progress info

* Fix HiddenAttr to carry value

* Refactored to internal variable

Changes made after discussion

* Implemented ActionItems for upload/download/remove

Replaced old Launcher approach, now it is not necessary after refactor of Ayon launcher.

* Update openpype/tools/ayon_loader/abstract.py

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

* Hound

* Refactor better retrieval of icon

* Refactor better readability

* Refactor renamed delegate

* Refactor better retrieval of icons

* Refactor better readability

* Refactor removed unneeded explicit refresh

* Hound

* Hound

* Hound

* Fix used wrong type

* Update openpype/tools/ayon_loader/ui/products_delegates.py

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

* Refactor renamed variable name

* Refactor formatting

* Added progress for representations

* cache version availability

* cache representations sync status

* changed representations count logic and moved it to products model

* site sync enabled is cached

* active and remote site names are cached

* small tweaks in site sync model

* change methods called by controller

* hide site sync columns if site sync not enabled

* use string conversion before iteration

* smal formatting changes

* updated abstract class with abstract methods

* renamed site sync model variable

* fixed method name

* fix used method name

* rename '_sitesync_addon' to '_site_sync_addon'

* fix remote site name cache

* small formatting changes in delegate

* modify site sync delegate to be more dynamic

* fix delegate painting

* do not handle repre progress in products model

* Add comma back

* simplify delegate code

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

openpype/tools/attribute_defs/widgets.py

@@ -608,7 +608,7 @@ class UnknownAttrWidget(_BaseAttrDefWidget):
 class HiddenAttrWidget(_BaseAttrDefWidget):
     def _ui_init(self):
         self.setVisible(False)
-        self._value = None
+        self._value = self.attr_def.default
         self._multivalue = False
 
     def setVisible(self, visible):