feat: preserve white spaces on Web

[OlimpiaZurek]

Add preserveSpacesInLabel property and preserveSpace method to Picker.item in Dropdown (Web only) In some cases (e.g. https://github.com/Expensify/App/issues/16329) users want to keep whitespace in Picker on Web (same as iOS and Android).

As on the web, a drop-down list is implemented using the element and by default the HTML element merges consecutive spaces into one space and cannot be changed, I added a helper method to achieve this goal and an additional prop based on which the users decide if they want to keep the whitespace or not.