Resume picker gains room for a footer note, wired for a 'starts in cloud' hint that is not turned on

What

The resume picker is the list you choose a past session from when you resume one. It can now show an optional note line beneath the list.

• The list takes a new footerNote. When it is set, the list reserves an extra row for it, but only if the text fits the width and there is enough height. The list's size calculation changed to match.
• The picker also takes a new startsInCloudByDefault setting, which feeds the footer note.
• The code that builds that note returns nothing, and the only caller found passes startsInCloudByDefault: !1 (false), so no note appears.

Why

This is groundwork for a hint in the resume picker about sessions starting in the cloud by default. Nothing you can see turns it on yet, so the picker looks the same for now.