Add where parameter and deprecate filters parameter

[guvra]

New filter syntax:

tables:
    customer:
        where: 'email like "%@test.org" or created_at > date_sub(now(), interval 55 day)'

A query validator is making sure that the query does not include any dangerous statement (execute, drop, alter...).

The PR deprecates the filters param.
This param is restrictive, and it already allows to inject raw SQL in some way (with expr: syntax), so it's barely more secure than a plain where.