context CHANGE rename ly_ctx_module_implement() to lys_set_implemented()

Backward compatibility with libyang 1.x, the new name also better fits to
the functionality.
diff --git a/src/tree_schema.h b/src/tree_schema.h
index d1eb3bd..179ac8c 100644
--- a/src/tree_schema.h
+++ b/src/tree_schema.h
@@ -1933,6 +1933,16 @@
                                   const char *name, size_t name_len, uint16_t nodetype, int options);
 
 /**
+ * @brief Make the specific module implemented.
+ *
+ * @param[in] mod Module to make implemented. It is not an error
+ * to provide already implemented module, it just does nothing.
+ * @return LY_SUCCESS or LY_EDENIED in case the context contains some other revision of the
+ * same module which is already implemented.
+ */
+LY_ERR lys_set_implemented(struct lys_module *mod);
+
+/**
  * @brief Check if the schema node is disabled in the schema tree, i.e. there is any disabled if-feature statement
  * affecting the node.
  *