Port citation to CITATION.cff format

[oerc0122]

Description of work
Migrate citations to standard CITATION.cff format

Fixes
N/A

To test
No code changes.
Verify details.
Can add ORCIDs, should add all contributors?, etc

[MBartkowiakSTFC]

The MDANSE_GUI package was written from scratch and I am pretty confident that the code of the GUI contains contributions from the following authors, listed alphabetically:
Raunakk Banerjee
Maciej Bartkowiak
Rob Buchanan
Chi Y. Cheng
Eric Pellegrini
Jacob Wilkins

In the case of MDANSE package and the documentation, I am not always able to attribute code to a specific author. This is the largest list of possible MDANSE authors that I managed to come up with, listed alphabetically:
Bachir Aoun
Raunakk Banerjee
Maciej Bartkowiak
Rob Buchanan
Vania Calandrini
Paolo Calligari
Chi Y. Cheng
Miguel Angel Gonzales
Gael A. Goret
Konrad Hinsen
Mark Johnson
Gerald Kneller
Franz Lang
Ashley Meigh
Sanghamitra Mukhopadhyay
Krzysztof Murzyn
Eric Pellegrini
Remi Perenon
Tomasz Rog
Slawomir Stachura
Rastislav Turanyi
Jacob Wilkins