Removing the `All` data constructor from  the `Lang` datatype has
several benifits, the main one being that we now have total functions
for things like `toISO693`.

This will make possible to write an uniform interface for stemming
`stem :: Lang -> StemmingAlgorithm -> T.Text -> T.Text`, as now
`Lang` will always map to a valid (ISO693) language.

This reverts commit efbe327f, reversing
changes made to 6d9bcd07.

We have contexts.hash_id which is enough (computed by postgres as a
trigger).

Merge remote-tracking branch 'origin/314-node-phylo-change-the-default-value-of-findancestors-to-false' into dev

We use for now an initial translation into Haskell of
this Javascript implementation:

https://github.com/words/lancaster-stemmer/blob/main/index.js

More tests needed

Test failed, not merging.

This reverts commit 2e77bfa5, reversing
changes made to fe201115.