add DropdownFeatherIcon for consistent look.

[maharshivpatel]

When we provide icon string in <Dropdown /> like below.

<Dropdown
	:options="[
		{
			group: 'Print Designer',
			hideLabel: true,
			items: [
				{
					...
					icon: 'plus',
				},
			],
		},
	]"
/>

It uses <FeatherIcon /> with some classes here.
however, when we want to create sub-menu by passing component like this one in builder

we need to copy mr-2 h-4 w-4 flex-shrink-0 text-ink-gray-6 in component where we use <FeatherIcon /> for consistent look. also, there is possibility that if/when classes are changed in frappe-ui there will be inconstancies.

proposed solution: have <DropdownFeatherIcon /> that can be used in components for consistent look

[maharshivpatel]

@netchampfaris thoughts ?