[Feature Request] Decouple Panel size, applet padding, and icon size

[HenryJk]

Issue/Description:
In current version of cosmic, applet padding and its icon size is fundamentally tied to the panel size. This makes certain level of information density impossible. For example:

This is my current plasma setup

This is my attempt of replicating it in cosmic

Display scaling in both is 135% (125% + 10% in cosmic), however, notice that in cosmic the clock applet, network applet, battery applet, etc, all have small icon compared to the space it can use.

I have noticed that in cosmic-panel, the padding and icon size is calculated from the panel size itself using some preset or formula. I'm requesting a feature to set the icon size and padding manually so that users can achieve their most comfortable information density while preserving the current preset as "default option" or "suggested option" instead.