[flexiglass] Adds horizontal spacing to status bar section.

Title says it all.

Before: https://screenshot.googleplex.com/AKpGm2FmngibHrM
After: https://screenshot.googleplex.com/BJgQKbjpqUfum62
Non-flexiglass, for reference: https://screenshot.googleplex.com/BsteXeQqsGkvPo7

Bug: 316211368
Test: see screenshots above
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT
Change-Id: I10c4cbc51667d9a717a0c8bba11e0dad9239c553