Coords kwarg added to plot_autocorr function

[lucifer4073]

Fixes #2288

Added the coords keyword argument to the plot_autocorr function in ArviZ. Used to specify variable names to be plotted. Made it consistent with other plotting functions such as plot_forest and plot_trace.

Example usage:

axes = az.plot_autocorr(
   data,
   var_names=["mu", "theta"],
   coords={"school": ["Deerfield", "Hotchkiss"]},
   backend="matplotlib"
)

Other points:

• Test case added -> test_plot_autocorr_coord
• Example for plot_autocorr modifed to show utility of the coords keyword.

---

📚 Documentation preview 📚: https://arviz--2404.org.readthedocs.build/en/2404/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.72%. Comparing base (adb2fef) to head (005e2d7).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2404   +/-   ##
=======================================
  Coverage   86.72%   86.72%           
=======================================
  Files         124      124           
  Lines       12908    12910    +2     
=======================================
+ Hits        11194    11196    +2     
  Misses       1714     1714           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.