<Downshift> ignores initialInputValue, initialSelectedItem

[david-morris]

• downshift version: 9.0.8 (also 8.1.0)
• node version: v18.17.1
• npm (or yarn) version: pnpm 8.7.5

Relevant code or config

    <Downshift<ItemData>
      onChange={selection => selection && onItemSelected(selection)}
      {...{
        initialInputValue,
        initialSelectedItem,
        onInputValueChange,
        itemToString,
        inputValue,
      }}
      initialInputValue="test"
    >

What you did:
I passed initialInputValue, initialSelectedItem, and then both in an attempt to change the initial value received from getInputProps().

What happened:
Initial value and selected item were empty, and the itemToString function was never called until an item was selected.

Reproduction repository:

None

Problem description:
<Downshift> component did not honor initialInputValue or initialSelectedItem

Suggested solution:

Fix any bug, document any applicable situation where it doesn't make semantic sense for the Downshift component to respect initial values.