Add icon to mobile close action

[Phillipxh]

What changed

• add the shared close icon to the mobile close menu item
• apply the change to document, spreadsheet, presentation, and Visio editors
• remove the legacy 36 px title indentation now that the item has a media icon

Why

The close action under Feedback & Support was the only menu action without an icon. Its placeholder indentation also pushed the label farther right than neighboring items.

Validation

• production mobile build: document editor
• production mobile build: spreadsheet editor
• production mobile build: presentation editor
• production mobile build: Visio editor
• git diff --check