Add 'Section administration' to Settings block

When viewing an individual section following the work in MDL-32508, it would be helpful to have a Section administration tree in the Settings block.

The use case is:

• user is viewing section
• notices typo/mistake in title/description and wants to correct. The user has to:
  • turn editing
  • then click the edit icon for the section
  • make changes
  • turn editing off

An alternative would be:

• user is viewing section
• notices typo/mistake in title/description and wants to correct. The user:
  • clicks the Settings -> Section administration -> Edit section
  • make changes

This could also have:

• highlight within course (for topics)
• show/hide