This makes all fields in a MatrixFile final and
the object therefore stateless. It also moves
all calculations into the isolate. After some
benchmarks it seems that this does not
really speed up the thumbnail creation
but it does no longer block the UI for
some seconds.
- By using [package:image](https://pub.dev/packages/image), the
`MatrixImageFile` was given automatically generated width and heigth.
- Moreover, `MatrixImageFile` was given a factory to create the image
file from a given maximal dimension.
- When sending images without explicitly providing a thumbnail, the
thumbnail is automatically generated based on the provided image.
- The blur hash in generated automatically based on the provided image.
Fixes:
https://gitlab.com/famedly/company/frontend/famedly-web/-/issues/162, https://gitlab.com/famedly/fluffychat/-/issues/756
Signed-off-by: Lanna Michalke <l.michalke@famedly.com>