fix issue with images not saving when creating a new slide

[RyanCoulsonCA]

Related Item(s)

#344, #355

Changes

• Fixes an issue with images not saving correctly if you upload an image and then create a new slide right after.
• Also fixes a problem with images disappearing after swapping language configs.

Notes

I couldn't figure out what exactly $nextTick was being used for here, but I've done a bunch of testing and everything seems to work properly. Let me know if you find anything.

Testing

Steps:

1. Open the demo page and load a product.
2. Create an image panel and upload an image.
3. Before pressing save or switching off the panel, create a new slide.
4. Switch back to the image panel and ensure the image is still being displayed.

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This change is 

[github-actions]

Your demo site is ready! 🚀 Visit it here: https://ramp4-pcar4.github.io/storylines-editor/fix-344

[yileifeng]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @RyanCoulsonCA)

[dnlnashed]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @RyanCoulsonCA)

[szczz]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @RyanCoulsonCA)