Clean up DatastoreAccess' interface

The schema() getter is supposed to be a part of the public interface.
The other methods within SysrepoAccess are just an implementation
detail, though.

Change-Id: I0599dcd1609568c45aecd8dec4c5df4d1b629e6d
diff --git a/src/datastore_access.hpp b/src/datastore_access.hpp
index 67b3d29..72e3553 100644
--- a/src/datastore_access.hpp
+++ b/src/datastore_access.hpp
@@ -34,6 +34,8 @@
     std::string m_what;
 };
 
+class Schema;
+
 class DatastoreAccess {
 public:
     virtual ~DatastoreAccess() = 0;
@@ -44,6 +46,8 @@
     virtual void createListInstance(const std::string& path) = 0;
     virtual void deleteListInstance(const std::string& path) = 0;
 
+    virtual std::shared_ptr<Schema> schema() = 0;
+
     virtual void commitChanges() = 0;
     virtual void discardChanges() = 0;
 };