MDEV-11146 SP variables of the SET data type erroneously allow values with comma

There was a duplicate code to create TYPELIB from List<String>:
- In typelib() and mysql_prepare_create_table(), which was used to initialize
  table fields.
- create_typelib() and sp_prepare_create_field(), which was used to initialize
  SP variables.
create_typelib() was incomplete and didn't check for wrong SET values.

Fix:
- Moving the code from create_typelib() and mysql_prepare_create_field()
  to news methods Column_definition::create_interval_from_interval_list()
  and Column_definition::prepare_interval_field().
- Moving the code from calculate_interval_lengths() in sql_table.cc
  to a new method Column_definition::calculate_interval_lengths(), as it's now
  needed only in Column_definition::create_interval_from_interval_list()
- Reusing the new method Column_definition::prepare_interval_field() in both
  mysql_prepare_create_table() and sp_prepare_create_field(), instead of the
  old duplicate code pieces
- Removing global functions typelib() and create_typelib()

This patch also fixes:
MDEV-11155 Bad error message when creating a SET column with comma and non-ASCII characters
The problem was that ErrCongString() was called with a wrong "charset" parameter.

sql/sql_table.h

@@ -251,7 +251,8 @@ bool quick_rm_table(THD *thd, handlerton *base, const char *db,
                     const char *table_name, uint flags,
                     const char *table_path=0);
 void close_cached_table(THD *thd, TABLE *table);
-void sp_prepare_create_field(THD *thd, Column_definition *sql_field);
+bool sp_prepare_create_field(THD *thd, MEM_ROOT *mem_root,
+                             Column_definition *sql_field);
 int prepare_create_field(Column_definition *sql_field,
 			 uint *blob_columns,
 			 longlong table_flags);