Refactor column picker typing

[PowerKiKi]

Refactor as described below for easier usage. Because the only non-ES2020 project is Dilps and we don't use ColumnPicker there.

natural/projects/natural/src/lib/modules/columns-picker/types.ts

Lines 5 to 12 in 7f69a2c

	* Implementation details:
	*
	* Unfortunately, we cannot use a `Record<AvailableColumn>` where keys would implicitly be unique and would replace
	* this ID property, because only ES2020 guarantee the order of object keys, and we must still support ES2015 for
	* iPhone 6. So, instead of `Record<AvailableColumn>`, we use `AvailableColumn[]` for now. But this could be
	* revisited once we drop support of ES2015.
	*
	* @see https://stackoverflow.com/questions/30076219/does-es6-introduce-a-well-defined-order-of-enumeration-for-object-properties