Implement sqlftw/sqlftw sql parser based type narrowing

[staabm]

just a ugly prototype to do the first steps and learn how sqlftw works.

the PR as narrows the return type of count() expressions to 0|positive-int in combination with the native type range

function countInference(\Dibi\Connection $conn): void
{
    $conn->fetch('SELECT count(email) as myemail, count(email) from ada');
}

relevant upstream issues

• SimpleName->getFullName() SQLFTW/sqlftw#16
• Wrong AST in self-joined query SQLFTW/sqlftw#17

see mysql functions list at https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html

Closes #460
Closes #248

[staabm]

we should make this inference disabled by default and allow to enable it via RuntimeConfiguration for now.

reasons

• stabilize
• sqlftw is pretty recent and therefore it should be able to disable it, to make sure we don't run into dead-ends
• sqlftw atm requires php 7.4, so this feature does not work for all versions supported by phpstan-dba