PAINTROID-457: Add .ora support while Save/Load

[msesko]

Someone can continue working on the tests for this ticket. I am done with my hours :)

Ticket
Paintroid-457 : Flutter: Add .ora support while Save/Load
https://catrobat.atlassian.net/browse/PAINTROID-457

New Features and Enhancements

Support for ora format image while saving/loading.(Emulator recording attached)
https://github.com/Catrobat/Paintroid-Flutter/assets/78733360/e0c2c9e2-061b-4776-8d17-890a297a0e15

Refactorings and Bug Fixes

Refactorings and Bug Fixes

Checklist

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