Add Linear Advection Diffusion Reaction Operator to ElmtOps

Issue/feature addressed

Did not have a linear advection diffusion reaction operator to duplicate functionality in Collections/MatFree libraries

Proposed solution

Building on Helmholtz operator add in an advection term.

Implementation

Followed local patterns for Serial/AVX and Device. i have not added StdMat versions.

Tests

Added test for all devices

Suggested reviewers

Jacues

Checklist

• [ ] Functions and classes, or changes to them, are documented.
• [ ] User guide/documentation is updated.
• [ ] Changelog is updated.
• Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).