refactor: use generics for Pointer func

[Tinyblargon]

Removed the type specific pointer creation functions and replaced it with one that uses generics.
Created the util package in the internal folder as the integration tests where using the old pointer functions. Putting it in internal ensures it can't be imported by a third party project.

Before:

func PointerString(text string) *string {
	return &text
}

// Creates a pointer to an int
func PointerInt(number int) *int {
	return &number
}

// Creates a pointer to a bool
func PointerBool(boolean bool) *bool {
	return &boolean
}

After:

func Pointer[T any](item T) *T {
	return &item
}