[Design] Implement the bloom effect

[bmarty]

Waiting for design confirmation.
@jmartinesp has already started working on it.

[jmartinesp]

I think I have a working implementation at the moment as a whole component, but I'd rather move to a Modifier solution.

The implementation:

• Is based on BlurHash to generate the blur used based on some loaded Bitmap, so we have to find out how to integrate it with Coil. This avoids having to use RenderEffect for blurring, which only works on Android 12+, and it's quite efficient if we only calculate it once: since it's based on a single Bitmap it might not work great if we enable animated avatars.
• Given the currently picked blend modes for the 'blurred layers' (HardLight, Saturation), we can only make it work down to API 29 (Android 10). In lower APIs the Bloom effect won't be visible. It's a shame, but it just isn't technically feasible to backport it any further.