SpriteCollab portrait downloader

[theCapypara]

Add a downloader for portraits to the portrait editor

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Beep, boop, I'm a bot! This issue was created by @Parakoopa in #skytemple.

[riiswa]

It's about adding a button on each portrait to be able to download it? (Like the new delete button)

[theCapypara]

Hm, I'd add one button that maybe opens a dialog? You'd also need to be able to select the form and probably a preview. Also, the "backend logic" for this is already in the randomizer (for reference): https://github.com/SkyTemple/skytemple-randomizer/blob/master/skytemple_randomizer/randomizer/portrait_downloader.py#L70

[theCapypara]

This is done.