Feat/list icon size

[PeterTorki]

Summary

Adds a new iconSize prop to List.Icon allowing consumers to set a custom icon size instead of the fixed 24px default.

Motivation

Previously, List.Icon always rendered at 24px, which limited flexibility. This change makes it possible to scale icons up or down based on design needs.

Example

<List.Icon icon="calendar" iconSize={32} />
<List.Icon icon="equal" iconSize={18} />

[callstack-bot]

Hey @PeterTorki, thank you for your pull request 🤗. The documentation from this branch can be viewed here.