Bogus.Tools.Analyzer generates 'default' RuleFor() for nullable system types rather than using the randomizer and .OrNull()

### Bogus NuGet Package

35.6.0

### .NET Version

net 6

### Visual Studio Version

17.10.3

### What operating system are you using?

Windows

### What locale are you using with Bogus?

en_US

### Problem Description

When a nullable system type is specified, the output RuleFor() is 'default'.

Perhaps this is by design, but it seems one would generally want to have the full spectrum of possible results for a nullable system type.

### LINQPad Example or Reproduction Steps

```
public class NullableProperties
{
public string FirstName { get; set; } = string.Empty;
public decimal? NullableDecimal { get; set; }
public int? NullableInt { get; set; }
public int JustInt { get; set; }
}

static void BogusAnalyzer()
{
var g = new Faker()
.RuleFor(n => n.FirstName, f => f.Lorem.Word())
.RuleFor(n => n.NullableDecimal, f => default) // <-- Would expect this to be f.Random.Decimal().OrNull(f)
.RuleFor(n => n.NullableInt, f => default) // <-- Would expect this to be f.Random.Int().OrNull(f)
.RuleFor(n => n.JustInt, f => f.Random.Int());

var o = g.Generate();
}

```

### Expected Behavior

I'd expect that the generated RuleFor would have the underlying type and use the OrNull() from Bogus, such as:

```
var g = new Faker()
.RuleFor(n => n.FirstName, f => f.Lorem.Word())
.RuleFor(n => n.NullableDecimal, f => f.Random.Decimal().OrNull(f))
.RuleFor(n => n.NullableInt, f => f.Random.Int().OrNull(f))
.RuleFor(n => n.JustInt, f => f.Random.Int());
```

### Actual Behavior

default is output in the RuleFor()

### Known Workarounds

_No response_

### Could you help with a pull-request?

No

Start with the Bogus.Tools.Analyzer behavior shown in the LINQPad reproduction, focusing on nullable system types and the generated RuleFor() expressions. Reproduce the decimal? and int? cases, then verify that generated rules use the underlying randomizer with OrNull() rather than default.

Written by the indexing model from the issue text.