Remove null coalesce for methods with default argument

[peterfox]

Changes

• Adds a configurable rule (with framework defaults)
• Adds a value object to use with the rule
• adds tests
• updates docs
• Adds rule to code quality set

Why

The rule should be useful to reduce the use of null coalescing with methods and functions where the method can take a default argument.

Not that in some cases a null coalescing might still be needed, for instance, if a config key is set to null, as far as I'm aware, it would still return null over the default. The default is only used when a key is missing.

The rule also covers the scenario where null is set and removes it.

-config('app.name') ?? false;
+config('app.name', false);
-config('app.name') ?? null;
+config('app.name');

-(new \Illuminate\Http\Request())->input('value') ?? '';
+(new \Illuminate\Http\Request())->input('value', '');

-\Illuminate\Support\Env::get('APP_NAME') ?? '';
+\Illuminate\Support\Env::get('APP_NAME', '');