Plainly exported strings default to type string hints in GDScript 2.0

[willnationsdev]

Godot version:
4566db2

OS/device including version:
Windows 10 Home Edition

Issue description:
When attempting to export a string variable in GDScript, as one would have done in GDScript 1, rather than display a LineEdit, it displays a GUI in the Inspector that has you select an Object type to assign to the string value. This appears to be because the @export annotation hardcodes the property hint to be PROPERTY_HINT_TYPE_STRING when I really don't want any sort of type specification.

We can fix it by properly creating appropriate export annotations for each case, since it appears that we are creating dedicated export annotations for every used hint string and not bothering with any sort of export inference.

1. @export which just exports things plainly and uses PROPERTY_HINT_NONE.
2. @export_type_string(str) which does what @export currently does.

Steps to reproduce:

extends Resource
class_name MyData
@export
var name := "hello"

Then, create a new MyData in the Inspector to see the result.

Minimal reproduction project:
The steps are trivial enough that it isn't necessary.