#26602 Path cache (folder) synchronization

Prior to a context being loaded up in the main window, the path cache is now synced. This is to ensure that the local caches (and folders) are up to date. 
In particular, this covers the use case where an object has been renamed, folders have been unregistered and new folders have been created. If the local path cache is out of date at this point, it will be unaware of the change and still contain the cache old entries.

Uses new core APi method `tk..synchronize_filesystem_structure()`