Make project state check in CREATE_CHANGE explicit

The majority of code in {Project,Ref,Change}Control is now about
permissions, but not all. Exceptions include checks for a project's
state. This is confusing, because users are presented with an exception
telling them that they lack some kind of permission while the real
reason for the failed operation is that the project's current state
doesn't permit the operation.

This is part of a series of commits to remove all project state checks
from *Control classes and make explicit checks instead.

This commit also adds intermediary checks for project state to
ChangeControl to keep the individual changes small. These will be
removed in subsequent commits.

Change-Id: I6db9c5e7ecf5d4f7b18bb5446522651236798e12

java/com/google/gerrit/server/git/receive/ReceiveCommits.java

@@ -1521,6 +1521,10 @@ class ReceiveCommits {
       reject(cmd, denied.getMessage());
       return;
     }
+    if (!projectState.statePermitsWrite()) {
+      reject(cmd, "project state does not permit write");
+      return;
+    }
 
     if (magicBranch.isPrivate && magicBranch.removePrivate) {
       reject(cmd, "the options 'private' and 'remove-private' are mutually exclusive");