Data usage label width, locking, Wi-Fi fixes.

Avoid wrapping sweep labels when underlying string is long, and avoid
showing blank "^1" sweep labels.  Only offer "restrict data" when
mobile networks are present.  Add locking around UidDetailProvider.

Move to isNetworkSupported() for consistency.

Bug: 5492495, 5471602, 5439402, 5373465
Change-Id: I79f5938d45ffbb4c2c242106424a466042a26c1c