Add HEIC support for iPhones

[RahulR100]

I added this package to core packages as I believe that without it, significant functionality is lost (no photos taken on an iPhone using the default HEIC format can be uploaded). The package is also < 30Mb so it's pretty light weight.

[IndrekHaav]

I'm not entirely convinced this should be a core package, if it's only needed for one specific format.

Also, wouldn't the libheif1 package suffice? The one you added (libheif-examples) seems to include example applications, which I don't think would be necessary. Not sure what the size difference would be, though.

I'll need to find some sample HEIF images and do some testing.

[RahulR100]

Hmm... I will do some testing with libheif1 but it does seem like it would cut it.

As for it being a core package... I could add this to optional and a note specifying that most photos from an iPhone would not work without this package.