Configure signed push verification on a per-project basis

Add a new inheritable boolean "enableSignedPush" to configure the
hook for each project, assuming it is enabled for the server. For the
default case, where it is not configured on the server, do not
surface this value in the UI at all.

Change-Id: I51baab5bfc15607a3c47ee8752b10d4972e8550e

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/Project.java

@@ -96,6 +96,8 @@ public final class Project {
 
   protected InheritableBoolean createNewChangeForAllNotInTarget;
 
+  protected InheritableBoolean enableSignedPush;
+
   protected Project() {
   }
 
@@ -108,6 +110,7 @@ public final class Project {
     requireChangeID = InheritableBoolean.INHERIT;
     useContentMerge = InheritableBoolean.INHERIT;
     createNewChangeForAllNotInTarget = InheritableBoolean.INHERIT;
+    enableSignedPush = InheritableBoolean.INHERIT;
   }
 
   public Project.NameKey getNameKey() {
@@ -171,6 +174,14 @@ public final class Project {
     this.createNewChangeForAllNotInTarget = useAllNotInTarget;
   }
 
+  public InheritableBoolean getEnableSignedPush() {
+    return enableSignedPush;
+  }
+
+  public void setEnableSignedPush(InheritableBoolean enable) {
+    enableSignedPush = enable;
+  }
+
   public void setMaxObjectSizeLimit(final String limit) {
     maxObjectSizeLimit = limit;
   }