Update Phobos navbar to reflect new std.container submodules.

The current navbar doesn't take into account the new submodules of `std.container`, and links to stale files. This PR updates the links and adds the new submodules to the left panel for easier navigation.

Depends on: https://github.com/D-Programming-Language/phobos/pull/2771

Cf: https://issues.dlang.org/show_bug.cgi?id=13766