Expose `is_last_member` to members view

What does this MR do and why?

For #24047 (closed). Currently if a member is the last owner the remove button is not shown. This can be confusing so we want to add a message in the modal explaining why the member can not be removed. To do this we need to be able to identify on the frontend which member is the last owner. This MR exposes a is_last_member property to the frontend.

From Vue dev tools

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