HeredocIndentationFixer - config option for indentation level

[gharlan]

We discussed the best indentation level for the HeredocIndentationFixer here and here.

But now since I'm actually using it, I changed my mind.
I would like to write code like this:

    public function foo() 
    {
        return $this->createQuery(<<<'DQL'
            SELECT foo
            FROM App\Entity\Foo foo
            WHERE ...
        DQL)->getResult();
    }

and NOT:

    public function foo() 
    {
        return $this->createQuery(<<<'DQL'
            SELECT foo
            FROM App\Entity\Foo foo
            WHERE ...
            DQL)->getResult();
    }

So I suggest to add a config option indentation with possible values start_plus_one (default; same as current behavior) and same_as_start (new behavior). (Ideas for better names?)

The fixer will remain non-risky, so it does not change the actual string result.
This input:

    $dql = <<<'DQL'
SELECT foo
FROM App\Entity\Foo foo
DQL;

will be changed with the new behavior (same_as_start) to:

    $dql = <<<'DQL'
    SELECT foo
    FROM App\Entity\Foo foo
    DQL;

Adding one more indentation level inside string content is not part of this fixer (as it would be risky).

[SpacePossum]

Thank you @gharlan.