After UX research, the conclusion is that all formats should use "section"
and not try to use alternative terms such as topic or week.
This commit replaces topic and week references with section. A couple of
considerations:
- Most of the strings in topics and weeks formats have been removed. In that
particular case it's not required to follow the deprecation process because
they will be using the generic ones defined in moodle or courseformat.
- The sectionname will be renamed from "Topic"/"Week" to "New section" in
MDL-80460.
785d3fd1e7