Missing: GDF to openPMD format

[sanjeev-one]

Add Functionality for .GDF to .h5 openPMD Format Conversion

Description

The current codebase lacks functionality to convert .GDF files to a .h5 openPMD format.

Example Script for Conversion

An existing script that performs this conversion is available in this repository:
openPMD-converter-GDF

Suggested Environment for Running the Example Script

To run this script, it is recommended to set up a conda environment with Python 3.6.5. The requirements.txt file should be modified as follows to ensure compatibility:

# openPMD_to_gdf.py, gdf_to_openPMD.py
openpmd-api>=0.13.0,<0.15.0
# gdf_to_openPMD.py
matplotlib>=3.0.0
# OpenPMD_add_patches.py
h5py>=2.8.0
numpy>=1.16.0```