Use IFileSource for the Source property of LutEffect #1426
Description
Is your feature request related to a problem? Please describe.
In #1425, the file path referenced will be saved as a relative path, so the LutEffect.Source property will also be changed to be saved as a relative path.
Describe the solution you'd like
Change the type of the LutEffect.Source property to IFileSource. Also, implement a UI for selecting IFileSource.
Describe alternatives you've considered
No response
Additional context
No response