fix missing indexes by quoting schema/table name to ::regclass (#711)

The same approach is used in pkg/statements/sql/table_schema.sql
and a sample reproduction for the bug is:

  CREATE SCHEMA test;
  CREATE TABLE test.data (id INTEGER PRIMARY KEY, name TEXT);
  CREATE UNIQUE INDEX "test.data_uniq" ON test.data (name);

Only the primary key is shown, and not the index created above.

pkg/statements/sql/table_indexes.sql

@@ -1,6 +1,6 @@
 SELECT
   indexname AS index_name,
-  pg_size_pretty(pg_table_size((schemaname || '.' || indexname)::regclass)) AS index_size,
+  pg_size_pretty(pg_table_size(('"' || schemaname || '"."' || indexname || '"')::regclass)) AS index_size,
   indexdef AS index_definition
 FROM
   pg_indexes