Home Screen: Update Store Management (Quick Links) icons

[mattsherman]

The icons used in the Store Management (Quick Links) card on the home screen should be updated to match the intended design.

This will likely involve updating the QuickLinks component to use Icon from @wordpress/icons instead of Icon from @wordpress/components.

Hm, is that the core Icon component? They should be there because I added them.

At least, I added the ones that I thought were missing, maybe some others need updating from their Dashicon counterparts 🤔

Here's the explicit list of icons to use;

* Market my store - [Megaphone](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/megaphone.js)

* Add products - [Box](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/box.js)

* Personalize my store - [Brush](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/brush.js)

* Shipping settings - [Shipping](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/shipping.js)

* Tax settings - [Percent](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/percent.js)

* Payment settings - [Payment](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/payment.js)

* Edit store details - [Pencil](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/pencil.js)

* Get support - [Lifesaver](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/lifesaver.js)

* View my store - [External](https://github.com/WordPress/gutenberg/blob/master/packages/icons/src/library/external.js)

It looks like the Brush and Pencil icons will need to be updated to match the visual design of the others, but we'll handle that in core :)

Original discussion of what icons to use in #4350:
#4350 (comment)