Usability improvements for migrations with addSql and parameters

[gbirke]

The addSqlmethod accepts parameters for creating inserting in a query. This is very useful for data migrations. However, the usability could be improved:

1. By adding an example to the docs that uses placeholders and a parameters array (or links to http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/data-retrieval-and-manipulation.html where the placeholder syntax is explained)

2. By including them in the output of --dry-run

[stof]

Can you send a PR addign a link to the DBAL documentation in the relevant place ?

[metalmini]

+1 on the "By including them in the output of --dry-run" comment

[mikeSimonson]

@gbirke @metalmini
Can you explain what you mean by adding them in the output of --dry-run ?

[aaa2000]

I think that adding them in the output of --dry-run means:

$this->addSql('INSERT INTO FOO VALUES(?)', [10]);

migrations:migrate --dry-run should not only display like that

INSERT INTO FOO VALUES(?)

but rather

INSERT INTO FOO VALUES(?) with parameters [10]

But there will be problems with big parameters array. (With long text, binary value)

[mikeSimonson]

@aaa2000 Well I would accept both the PR on the doc and the dry run improvements.