Apply @RequiresCapability to REST API

Move the @RequiresCapability from SSHD to gerrit-extension-api. Modify
the RestApiServlet to check the current user has the required
capabilities. All RestApiServlets must now inject the currentUser
provider in their constructor and pass it to the super class.

Signed-off-by: Brad Larson <bklarson@gmail.com>
Change-Id: Iffc9bc99b8d2fafd07bf624008719b0ec647ce7d
20 files changed