fix: handle empty kwargs and high state update in high-to-low case

[abyesilyurt]

Bug fixes:

• Fixed is_execution_on_owned_args when kwargs is empty.
• Fixed ObjectDiff showing modified after syncing by applying empty state.
  Thanks @eelcovdw for the help.

Test updates:

• Updated tests to check for the bugs above.
• Extended twin api integration test. I need to update it with the changes from Custom api and worker #8693
• Seperated sync tests into two files. New one is using the new flow with resolve_single, while the old one is still using resolve.

Some extra prints and docs:

• Added a reminder to __getattribute__ error message to call .refresh().
• Added a docstr to AnyActionObject.
• Added a warning print when a widget has an unused share button.