Add setting for hiding blocked calls.

+ Add settings switch to blocked number settings.
+ Add utility for checking/setting whether calls should be blocked.
+ Filter out blocked calls in call log query, if appropriate.
+ Refresh call log fragment after a change in setting.

Followup work: delete voicemails for calls by blocked numbers after
the time when the user blocked them.

Bug: 24134270
Change-Id: I85088697559ef6fb446b82617f14f1c6fa893df1