PR Summary

Picked up from#21168. Adds anoffset parameter toMultipleLocator so the ticks can all be shifted by a given value.

importmatplotlib.pyplotaspltimportmatplotlib.tickerasmticker_,ax=plt.subplots()ax.plot(range(10))locator=mticker.MultipleLocator(base=3,offset=0.3)ax.xaxis.set_major_locator(locator)plt.show()

### To Do

1. Agree whetheroffset is the best name for the new parameter.
2. Address documentation tasks in the below checklist, but I wanted to get feedback on the principle and the parameter name before I went all in.

PR Checklist

Documentation and Tests

• Has pytest style unit tests (andpytest passes)
• Documentation is sphinx and numpydoc compliant (the docs shouldbuild without error).
• New plotting related features are documented with examples.

Release Notes

• New features are marked with a.. versionadded:: directive in the docstring and documented indoc/users/next_whats_new/
• [N/A] API changes are marked with a.. versionchanged:: directive in the docstring and documented indoc/api/next_api_changes/
• Release notes conform with instructions innext_whats_new/README.rst ornext_api_changes/README.rst