feat(admin-ui): IconPicker component

[leopuleo]

Changes

With this PR, we are upgrading the IconPicker component to ensure it complies with the new design system UI.

You'll find 2 IconPicker components:

webiny/admin-ui

This component was previously integrated into the @webiny/app-headless-cms and @webiny/app-page-builder packages. Both of these components now utilize the generic version exported by @webiny/admin-ui.

This component only renders icons from @fortawesome/react-fontawesome package.

webiny/app-admin

This component is utilised by @webiny/app-page-builder and is more flexible regarding which icons can be handled.

Other changes:

<DelayedOnChange />

This component has been transferred from @webiny/ui to the fresh @webiny/admin-ui.

Add forwardEventOnChange prop to <Input /> and <Textarea />

We introduce the forwardEventOnChange?: boolean prop; if set to true, the full event will be forwarded to the provided onChange callback. This prop was previously named rawOnChange.

<Popover />

We set the collisionPadding prop to prevent the component from colliding with the edge of the viewport.

How Has This Been Tested?

Manually

[adrians5j]

Initial review done. Overall, looks good ofc!

Extra questions below. Note: nr2 is probably good.

1. Should these be a bit darker?

2. This input is more gray in Figma.

3. Ah I guess it's because in Figma it's not focused. Still, found this placeholder to be a bit darker in Figma:

Maybe I just don't see it right. Can you dbl check?

4. Can you dbl check these paddings?

5. Should we ask Kreso to provide this? At least note it down somewhere for him?

6. Do we have an example where a component does not already have a value assigned to it? Like this?