CBC rz sweep chunk

[eappen-nelluvelil]

PR Checklist

• I have updated the user guide and/or Python API documentation if necessary.

Note: This PR builds on top of PR #1008. Once #1008 has been merged, this PR will be updated to remove #1008's commits and retain only the latest 2 commits. **~59% of the changes from the latest 2 commits come from regression tests. **

This PR adds host CBC support for 2D $r-z$ problems and corresponding regression tests adapted from the existing AAH tests. AAH and CBC $r-z$ sweep chunks reuse fixed-node SIMD-vectorized sweep kernel utilities where applicable.

The following CBC-specific absolute tolerances needed minimal adjustments relative to the corresponding AAH tests to get them to pass:

Test	Quantity	AAH gold/reference	CBC observed	Absolute difference	abs_tol change
transport_2d_cyl_2g_scatter_vacuum_cbc.py	G0_MAX	0.8429208738494	0.8429208719705	1.8789e-9	1e-9 to 2e-9
transport_2d_cyl_2g_scatter_vacuum_cbc.py	G1_MAX	0.3655486193072	0.3655486169397	2.3675e-9	1e-9 to 3e-9
transport_2d_cyl_disk_leakage_reflecting_bcs_cbc.py	Side leakage=	97.24863271745009	97.24862557253948	7.14491061e-6	1e-6 to 8e-6
transport_2d_cyl_disk_leakage_reflecting_bcs_cbc.py	Total leakage=	97.24863271745009	97.24862557253948	7.14491061e-6	1e-6 to 8e-6

[eappen-nelluvelil]

@wdarylhawkins @quocdang1998 Rebased PR on top of #1008. Once 1008 is merged, I'll update this PR remove 1008's commits.

[eappen-nelluvelil]

@wdarylhawkins @quocdang1998 Removed PR #1008 's commits from this PR, and it should be good to merge.