Show property record description next to array indices

[Yato333]

Changes

Part of https://github.com/iTwin/presentation/issues/654 Property record description (if present) will be shown next to the index for array property items. This should improve user experience when browsing through the property grid having many related instances.

With array items defined like this:

const arrayMembers = [
  PropertyRecord.fromString("Value 1", "Item 1"),
  new PropertyRecord(
    {
      valueFormat: PropertyValueFormat.Array,
      itemsTypeName: "string",
      items: [
        PropertyRecord.fromString("Value 2", "Item 2"),
        PropertyRecord.fromString("Value 3", "Item 3"),
      ],
    },
    { ... }
  ),
  new PropertyRecord(
    {
      valueFormat: PropertyValueFormat.Struct,
      members: {
        "Member 1": PropertyRecord.fromString("Value 3", "Item 3"),
        "Member 2": PropertyRecord.fromString("Value 4", "Item 4"),
      },
    },
    { ... }
  ),
].map((record, idx) => {
  record.description = `Description ${idx}`;
  return record;
});

Before:

After:

Testing

A unit test was added.

[Yato333]

@GerardasB there goes the NextVersion.md 😄 Added screenshots and updated NextVersion.md in #897