Confetti size system

[DanielMartinus]

Problem

• The current system to adjust and add sizes to confetti library is not ideal. It only lets you choose between three sizes which are relatively large on small mdpi screens because they are defined in pixels and were tested on large phone screens.
• konfetti.models.Size class has a confusing name since Size is also already used in the Android SDK

Solution

Currently thinking of rewriting this part of the system to allow the users to add any particle size to the system instead of having to rely on Size.SMALL, Size.MEDIUM and Size.LARGE.