Support the translation of the group title labels (and Help text)

Problem/Motivation

The group title label per group type should be translatable. This is very similar to this issue → and the fix is basically the same but for group_type. It's important to note these points → apply.

Note: Your group.type.your-group-type.yml file will need to have a langcode set or the translation form will 403.

Steps to reproduce

If you head to /admin/group/types/manage/{type}/translate/{langcode}/edit you should see an option to translate the Label and Help text as we do for other content types.

Proposed resolution

Introduce `GroupTypeMapper` to allow the translation of the Label and Help text.

Remaining tasks

User interface changes

Before:

After:

API changes

None

Data model changes

None