Create a skiplist

[coke]

We spend a lot of time and calculation every run to test every module in the ecosystem.

For those modules that are known to fail, we don't need to keep them testing every release.

Use the results from the last release, and anything showing as "AlwaysFail", add to a skiplist.

We can use the skiplist to track tickets opened with module authors, and to track versions - if we find a new version is available, we can then test and remove from the skiplist.

[coke]

See Essential.rakumod on coke/cleanup branch for an example.