rename Tvs to ConvexTvs

[mkerjean]

Motivation for this change

Rename the Tvs class of HB to ConvexTvs, as it describes the structure of locally convex topological vector spaces.

Checklist

• added corresponding entries in CHANGELOG_UNRELEASED.md

• added corresponding documentation in the headers

Reference: How to document

Merge policy

As a rule of thumb:

• PRs with several commits that make sense individually and that
  all compile are preferentially merged into master.
• PRs with disorganized commits are very likely to be squash-rebased.

Reminder to reviewers

• Read this Checklist
• Put a milestone if possible
• Check labels

[affeldt-aist]

Longer renaming just makes things more precise. I think that convexTvsType (rather than convextvsType) is more in line with the other namings so far though.

[affeldt-aist]

Don't mind the read CI: this is because of a Rocqnavi time out and ssprove that needs to be fixed.

[mkerjean]

Longer renaming just makes things more precise. I think that convexTvsType (rather than convextvsType) is more in line with the other namings so far though.

This has been addressed, as well as the .in the header.