Include the new 'tzip-drafts' folder in the TZIP explorer view.

Tzip repo was recently amended with a new directory called tzip-drafts where proposals that could become proper TZIPs are initially tracked.

https://gitlab.com/tzip/tzip/-/tree/master/drafts

At this point it is not clear how we should include this in the Tzip explorer. Requirements around this should be collected and the required changes should be implemented.