Use BitmapFactory on old versions of Android

[dfabulich]

ImageDecoder was introduced in API level 28 (P)

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• REQUIRED: I have signed the Contributor Agreement
• REQUIRED: I have tested my change locally with swift test
• OPTIONAL: I have tested my change on an iOS simulator or device
• OPTIONAL: I have tested my change on an Android emulator or device
• REQUIRED: I have checked whether this change requires a corresponding update in the Skip Fuse UI repository (link related PR if applicable)
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• OPTIONAL: I have added an example of any UI changes to the Showcase sample app
  Support Android 7 (API level 24) skipapp-showcase#108

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Cursor did a first draft; I refactored it. I tested it using skiptools/skipapp-showcase#108

[dfabulich]

I don't repro this CI failure on my machine. swift test passes for me.

[marcprux]

I don't repro this CI failure on my machine. swift test passes for me.

I'm seeing this on the main branch as well, probably a side effect of skip 1.9 and skiptools/skip#697

I'll fix the test cases, since these sorts of cosmetic drifts are not uncommon.