[11.x] Add deleteIf, forceDeleteIf and restoreIf methods

[jbrooksuk]

This PR introduces three new methods to the Model and SoftDeletes.

• deleteIf
• forceDeleteIf
• restoreIf

Oftentimes, I'll want to conditionally delete or restore a model and so this saves writing that additional wrapping condition (when will PHP get primitive if and unless?!).

Like all good Laravel methods, these methods use the value helper underneath, so you can pass a bool or Closure.

[henzeb]

Can't it be done with Conditional? When / unless ?

[jbrooksuk]

@henzeb yes, but then you would end up with:

$model->when(true, fn () => $model->delete());

vs.

$model->deleteIf(true);

[devfrey]

If we were to add an If/When/Unless variant to every framework method I wrap in a conditional statement we'd have a framework twice the size. Where does it end? Let's just embrace the PHP language and write if statements.

[jbrooksuk]

@devfrey I absolutely agree, and @taylorotwell said the same thing to me when I initially proposed this. However, you're more likely to want to conditionally delete or restore a model than you are to conditionally render a view or drop a field etc, where at that point, you do need to draw a line.

We do need to draw a line somewhere, but I do believe these three methods should be in the accepted side.

[NathanaelGT]

@henzeb yes, but then you would end up with:

$model->when(true, fn () => $model->delete());

vs.

$model->deleteIf(true);

You can shorten it with

$model->when(true)->delete();

[insathroof]

This PR just removes the need for an if/else, it's still useful. A much more useful PR than this was recently denied. If this is approved, I would ask you @jbrooksuk to recreate this PR: #51073, because Taylor will definitely approve it. It doesn't make sense for Taylor to act like this, choosing PR for its author, but if it's the only way, fine.

[henzeb]

This PR just removes the need for an if/else, it's still useful. A much more useful PR than this was recently denied. If this is approved, I would ask you @jbrooksuk to recreate this PR: #51073, because Taylor will definitely approve it. It doesn't make sense for Taylor to act like this, choosing PR for its author, but if it's the only way, fine.

What wrong with the following:

$model->when(true)->delete();

?