[PROPOSAL] new raw SQL action

## Motivation

Some simple sql queries have better optimization than LINO'pull algorithm (such as DISTINCT).

## Proposal

This is a proposal to add a new `sql` action. SQL query is read from standard input and result is dump as jsonline in standard output.

## Example

```bash
$ echo "select * from public.customer" | lino sql source
{"id" : 1, "name": "Robert"}
{"id" : 2, "name": "Nick"}
...
```