Implement int8, uint8, int16, uint16, int64, uint64 types

This sw did not support uint8 type, which is needed by the upcoming
driver CalibrationBox within cla-sysrepo, so we implemented uint8 and
other types in TODO sections.

Creating leaf_data_XXX_classes for all types would result in a lot of
redundant code so the base class was turned into a template and the type
is passed through the template argument.

Change-Id: I866a3933fe21ea7844299556e5aaf39b3e40e92f
Co-Authored-By: Jan Kundrát <jan.kundrat@cesnet.cz>
diff --git a/src/schema.hpp b/src/schema.hpp
index 87feeaa..145ab07 100644
--- a/src/schema.hpp
+++ b/src/schema.hpp
@@ -27,8 +27,14 @@
     String,
     Decimal,
     Bool,
-    Int,
-    Uint,
+    Int8,
+    Uint8,
+    Int16,
+    Uint16,
+    Int32,
+    Uint32,
+    Int64,
+    Uint64,
     Enum,
     Binary,
     IdentityRef,