add full-star input file and allow annotate latitude lines for xrb_spherical slice plot.

[zhichen3]

PR summary

PR motivation

PR checklist

• [ ] test suite needs to be run on this PR
• [ ] this PR will change answers in the test suite to more than roundoff level
• [ ] all newly-added functions have docstrings as per the coding conventions
• [ ] the CHANGES file has been updated, if appropriate
• [ ] if appropriate, this change is described in the docs

[zingale]

fyi, for scaling, there's also this simple script: https://github.com/AMReX-Astro/Castro/blob/main/Exec/science/flame_wave/scaling/frontier/avg_time.sh