Register the sticker reference provider only if the related task type is available

[julien-nc]

It was always registered so the sticker picker could be used even if:

• the "Enable text-to-sticker in smart picker" admin setting was disabled
• the "Enable text-to-sticker in smart picker" personal setting was disabled
• the "Generate sticker" task type was disabled in the AI admin settings

The main fix is

• Prevent loading the reference script if the "Generate sticker" task type is not available

Additional aspect of the fix for later:

• Prevent registering the sticker generation reference provider, task type and provider if the "Generate image" task type is not available (disabled in AI admin settings or has no provider). We kind of need taskProcessingManager->getAvailableTaskTypeIds for that (to efficiently check if the task type is available in Application.php) and we still support NC 30-31 which don't have this method.

Please try to test all scenarios in your dev setup:

• TextToImage not available (because it's disabled or there is no provider installed)
• TextToStickerTaskType not available because it's disabled
• "Enable text-to-sticker in smart picker" admin setting disabled
• "Enable text-to-sticker in smart picker" personal setting disabled

If all of those are enabled/available, the "AI sticker generation" picker should be there in the UI (I use Talk to test).

Additional fixes:

• Bug in personal settings
• Do no edit the value automatically when the admin settings are loaded
• Improve warning messages for picker toggles
• Make sticker generation tasks fail if image generation is not available
• Add admin setting warning if sticker generation is enabled while image generation is not available

[julien-nc]

@janepie I addressed all the topics we discussed.

The initial comment was updated.

[janepie]

Then let's go 🚀

[lukasdotcom]

I think I went through all the combinations to test. Looks good 🚀