Add a Unique Identifier property to ImageEffect instances

[gregcotten]

As discussed in #203

[garyo]

@gregcotten You should be able to test this in Silhouette now (per @barretpj at the TSC meeting). If it's all working, we can merge it.

[gregcotten]

@garyo can test in a day or so - head very much down at the moment!

[fxtech]

@gregcotten are you able to check the UUID stuff in Silhouette 2025.5 or 2026?

[fxtech]

NOTE: after discussing this, we need to update this PR with documentation explaining the limitations of this feature if plugins want to use it as a seed.

[gregcotten]

@fxtech, I've just installed and activated a trial for Silhouette 2026.0.2 but cannot figure out how to get it to load a OpenFX plugin...

[fxtech]

@fxtech, I've just installed and activated a trial for Silhouette 2026.0.2 but cannot figure out how to get it to load a OpenFX plugin...

Hey @gregcotten sorry I didn't see that!
In Silhouette 2026+ you need to whitelist the OFX plugins you want it to load. Go to Preferences->Plugins.

BUT - we agreed in the OFX Meeting that this shouldn't be used as a seed, due to the way timeline-based hosts work.
There MIGHT be a use for this in some cases but it shouldn't be used as a seed.

I have an alternate implementation in mind for seed use, which would be a new property on Int parameters that would that could provide that capability.