Provide a simple way to access the value of fetch.J

[glossd]

The package's only way to access the fetch.J value is with the Raw() method, but it's not very useful, because you need to do a type assertion and type switch after it.
Method fetch.J#String() can be used to access the strings, but it's not intuitive.
Perhaps fetch.J could have multiple methods that do type assertation.
e.g.

j, _ := fetch.Unmarshal[fetch.J](`[1, 2, 3]`)
arr, ok := j.Array()
if !ok {
    // not array
    // arr is empty
}

But this will not solve the problem of panicking if j is nill

[glossd]

fetch.J#Raw() won't panic on nil after version v0.2.0

[glossd]

Tbh the type assertation is the very similar to the example.

	j, _ := fetch.Unmarshal[fetch.J](`[1, 2, 3]`)
	arr, ok := j.Raw().([]any)
	if !ok {
		panic("not an array")
	} else {
		fmt.Println("Array:", arr)
	}

And if someone needs a specific return type they should use that particular type on the function's generic type.
fetch.J.String is convenient because it doesn't return any errors, only one string.
E.g. right now If one expects a number from fetch.J.Q, then they can do the type assertation or calling fetch.J.String to do a string conversion.
I could add bunch of methods to fetch.J - Number, Boolean, Array, Map and return the default value, but I don't think the default value should represent nil values, it will cause problems.

[glossd]

I wrote a function to safely convert all types

func JConvert[T bool | float64 | string | []any | map[string]any](j J) (T, bool) 

and compared all the type assertations

res, ok := j.Q(".category").Raw()(map[string]any)
res, ok := fetch.JConvert[map[string]any](j.Q(".category"))
res, ok := j.Q(".category").AsObject()

res, ok := j.Q(".tags").Raw()([]any)
res, ok := fetch.JConvert[[]any](j.Q(".tags"))
res, ok := j.Q(".tags").AsArray()

res, ok := j.Q(".price").Raw()(float64)
res, ok := fetch.JConvert[float64](j.Q(".price"))
res, ok := j.Q(".price").AsNumber()

res, ok := j.Q(".name").Raw()(string)
res, ok := fetch.JConvert[string](j.Q(".name"))
res, ok := j.Q(".name").AsString()

res, ok := j.Q(".sold").Raw()(bool)
res, ok := fetch.JConvert[bool](j.Q(".sold"))
res, ok := j.Q(".sold").AsBoolean()

I believe the winner is all the As* functions.