rename setD_closed to setSD_closed

[affeldt-aist]

Motivation for this change

This is a first step towards fixing the issue https://github.com/math-comp/analysis/issues/1225 : rename setD_closed to setSD_closed so that setDI_closed can be renamed setD_closed later.

Checklist

• [x] added corresponding entries in CHANGELOG_UNRELEASED.md

• [x] added corresponding documentation in the headers

Reference: How to document

Reminder to reviewers

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