Potential undefined behavior with read_flat_grid

[ews-ffarella]

Bug description

Yesterday, I think I canceled the IO operation when writing my terrain file. Instead of being 60mb, it was just 1mb. Trying out my terrain refinement, I just couldn't get the results I had before. Cost me a couple of hours of debugging
Short story: I think we should check that we actually are not at eof when reading the values. There must be a bug somewhere because basically, only half of my terrain was read.

https://github.com/Exawind/amr-wind/blob/main/amr-wind/utilities/io_utils.cpp#L13

Another common grid format is the Arcgis ASCII grid. https://gdal.org/en/stable/drivers/raster/aaigrid.html

It is a very simple format for raster data. Switching to this would make amr-wind more compatible with conventional GIS formats.

The drawback is that the cell size in x any y are constant, but I think that most users are ok with that

One would need to add:

TerrainDrag.file_format = AAIGRID / native?

This could be reused when specifying z0 and forest parameters. Thw current implementation / format is however much more memory friendly for small areas.

Steps to reproduce

Steps to reproduce the behavior:

1. Compiler used
   • GCC
   • LLVM
   • oneapi (Intel)
   • nvcc (NVIDIA)
   • rocm (AMD)
   • with MPI
   • other:
2. Operating system
   • Linux
   • OSX
   • Windows
   • other (do tell ;)):
3. Hardware:
   • CPU
   • GPU
4. Machine details ():

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5. Input file attachments
6. Error (paste or attach):

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7. If this is a segfault, a stack trace from a debug build (paste or attach):

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Expected behavior

AMR-Wind information

==============================================================================
                AMR-Wind (https://github.com/exawind/amr-wind)

  AMR-Wind version :: v1.4.0-17-g250778a3-DIRTY
  AMR-Wind Git SHA :: 250778a3306e96b46afc117fc722491acaeb6176-DIRTY
  AMReX version    :: 24.03-36-g748f8dfea597

  Exec. time       :: Fri May 10 09:51:15 2024
  Build time       :: May  8 2024 20:36:21
  C++ compiler     :: Clang 17.0.6

  MPI              :: OFF
  GPU              :: OFF
  OpenMP           :: OFF

  No additional third-party libraries enabled

           This software is released under the BSD 3-clause license.
 See https://github.com/Exawind/amr-wind/blob/development/LICENSE for details.
------------------------------------------------------------------------------

Additional context

[hgopalan]

We will discuss this internally and get back to you.