Make sure zio-config doesn't support values as list without proper indexing

[afsalthaj]

The library zio-config didn't mean to support considering any separated by comma as a list, since it already make use of indexed formats. All the configs handled by ZIO Config are indexed, and has a format that support list natively.

However, internally it was making using ConfigProvider.Flat.parsePrimitive which assumes a value that has strings separated by comma is a list

This support now removed (since the library should never make use of this feature), which will hopefully fix issues such as #1085

Example:

  {
     values: [1, 2, 3]
     complex_values : [

       {
          x : 10
          y : 11
       },

      {
         x : 12
         y : 13
      }
    ]
  }

Will be considered as

values[0] -> 1
values[1] -> 2
values[2] -> 3
complex_values[0].x -> 10
complex_values[0].y -> 11
complex_values[1].x -> 12
complex_values[1].y -> 13

Addition cleanups

• As a minor clean up, we have also moved xml into an experimental package, and updated the documentations
• Fixed examples
• Although not perfect yet, try to keep the order of list in the config