new table function: sqlrs_functions

[Fedomn]

Currently, we already have sqlrs_tables() and sqlrs_columns table function.

sqlrs/src/function/table/sqlrs_tables.rs

Lines 118 to 122 in 0bfe264

	set.add_table_functions(TableFunction::new(
	"sqlrs_tables".to_string(),
	Some(Self::bind_func),
	Self::tables_func,
	))?;

Then, we should implement more internal metadata table, such as:

• sqlrs_functions()