Some tweaks for AMR treatment in xdmf command

[akashdhruv]

• Add option for AMReX grid
• Only use AMR grid if changed (this avoids the computational burden to write grid files every time a plot file is created)

[alentner]

I have added an alternative modification to the create_xdmf library.

Specifically, the directory will be searched for a grid file matching (or less than) the number of the plot file and working backwards until a valid grid file is identified.

For example,

Directory:

- INS_LidDr_Cavity_hdf5_grd_0000
- INS_LidDr_Cavity_hdf5_grd_0002
- INS_LidDr_Cavity_hdf5_plt_cnt_0000
- INS_LidDr_Cavity_hdf5_plt_cnt_0001
- INS_LidDr_Cavity_hdf5_plt_cnt_0002
- INS_LidDr_Cavity_hdf5_plt_cnt_0003

Result

- INS_LidDr_Cavity_hdf5_plt_cnt_0000  <->  INS_LidDr_Cavity_hdf5_grd_0000
- INS_LidDr_Cavity_hdf5_plt_cnt_0001  <->  INS_LidDr_Cavity_hdf5_grd_0000
- INS_LidDr_Cavity_hdf5_plt_cnt_0002  <->  INS_LidDr_Cavity_hdf5_grd_0002
- INS_LidDr_Cavity_hdf5_plt_cnt_0003  <->  INS_LidDr_Cavity_hdf5_grd_0002

[alentner]

This has been implemented in #69