Add support for purely serial fields

[matt-frey]

In GitLab by @vinciguerra_a on Apr 24, 2023, 14:27

The current implementation generally assumes parallel decomposition for fields and does not support non-decomposed fields except when running on a single rank.

• Adapt BareField operations for all-serial fields
• Skip neighbor finding for layouts in all-serial fields
• FFTs for all-serial fields
• MPI communication in operations with all-serial fields

[matt-frey]

In GitLab by @vinciguerra_a on May 3, 2023, 14:30

created merge request !167 to address this issue