Option to specify north/south tilt for snowflake configurations

[Plasdom]

Description of changes

For snowflake configurations where the two X-points are nearby in flux coordinates, often the patch map generated by INGRID results in very small patches in some parts of the domain. This produces non-smooth grids which are hard to simulate in UEDGE. For example:

This can be fixed in part by specifying angles for the north/south directions out of each X-point in exactly the same way as for the east/west directions. This PR adds north/south tilt options for X-point 1 & 2 for all possible snowflake topologies (SF15, SF45, SF75, SF105, SF135, SF165). There are new input options:

grid_settings:
    patch_generation:
        xpt1_N_tilt: 1.8   # Angle of the 'north' direction out of X-point 1 (rads) 
        xpt1_S_tilt: -1.8  # Angle of the 'south' direction out of X-point 1 (rads)
        xpt2_N_tilt: 1.8   # Angle of the 'north' direction out of X-point 2 (rads)
        xpt2_S_tilt: -1.8  # Angle of the 'south' direction out of X-point 2 (rads)
        use_xpt1_N: true   # Whether to use X-point 1 'north' tilt angle
        use_xpt1_S: true   # Whether to use X-point 1 'south' tilt angle
        use_xpt2_N: true   # Whether to use X-point 2 'north' tilt angle
        use_xpt2_S: true   # Whether to use X-point 2 'south' tilt angle

In the above example, modifying the above settings appropriately increases the size of the 'F1' patch, producing a smoother grid:

I've added a new file to the example_files directory which demonstrates this functionality (example_files/SF45/SF45_mastu.yml).

How was this tested?

Locally, on example INGRID parameter files for all possible snowflake configurations.

Relevant issues

None.

Checklist

- [ ] I have added/updated tests relevant to this PR.
- [ ] I have updated any baselines required for the test suite.

• I have run the test suite locally to ensure my changes work as intended.

[bryan-garcia]

Looks good to me