Add SQL / DQL mutators

[Slamdunk]

Hi, given the raise of static analysis tools that can interpret both DQL (phpstan-doctrine) and SQL (phpstan-dba) I wonder if and how we can introduce mutators also for queries.

The main mutators I'm looking for to challenge queries in PR are:

1. Boolean Substitution
2. Negated Conditionals

There are a lot of considerations to take into account:

• How to we know a string is a SQL / DQL?
• Do we need to rely on external tools like the above mentioned static analyzer?
• Should this be an Infection extension rather than a new feature?
• How this copes with --git-diff-lines?

[maks-rafalko]

I had this idea for ages (framework/lib-specific mutators), so a big 👍 here.

If (when) we go with extracting our mutators to a separate package (#669), this can be just a "plugin" / repo with doctrine-related mutators. For now it's easier to integrate it as a profile/standard mutators into Infection core, IMO.

How to we know a string is a SQL / DQL?
Do we need to rely on external tools like the above mentioned static analyzer?

I don't know how difficult it will be, we touched it a couple of times, Ondrej suggested to integrate PHPStan's analyzer here #697 (comment). Seems like not an easy task from the first glance, keeping in mind possible performance implication.