Allow TUV-x grid data to be updated through the API

[mattldawson]

Add the ability for host applications to update grid data at runtime.

Acceptance Criteria

• Users can set the edge and mid-point values for any grid in the TUV-x configuration (heights, wavelengths(read-only))

Ideas

• Add grid_map_t and grid_t types to the tuvx_interface module, something like:

type :: grid_map_t
  type(c_ptr) :: ptr_ ! Pointer to internal tuvx_core%grid_warehouse_
end type

type :: grid_t
  type(c_ptr) :: ptr_ ! Pointer to specific grid in tuvx_core%grid_warehouse_
end type

• Add internal_get_grids_tuvx function to module tuvx_interface:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    function internal_get_grids_tuvx(tuvx) result(grids)
      use iso_c_binding, only: c_ptr, c_f_pointer
      type(c_ptr), intent(in) :: tuvx
      type(grid_map_t) :: grids

      type(core_t), pointer :: core

      call c_f_pointer(tuvx, core)
      grids%ptr_ = c_loc( core%grid_warehouse_ )

    end function internal_get_grids_tuvx

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

• do something similar for grid_t that looks up grids by name and units
• add grid_t::update_edges() and grid_t::update_mid_points()
• a user could do something like this:

   tuvx => tuvx_t( config_path )
   grids = tuvx%create_grids( )
   grid = grids%get( "height", "m" )
   call grid%update_edges( new_edge_data_array )
   call grid%update_mid_points( new_mid_point_data_array )