rename Close to avoid name ambiguity, fixing Windows build

[robx]

Somehow, we import GHC.Event.Windows.ConsoleEvent.Close on Windows
via Hasql.Pool.Prelude, which conflicts with Close.

• might be nicer to avoid that import, but I couldn't figure out where it even comes from precisely (and I wouldn't want to conditionally hide an import based on CPP...)
• should Windows be added to CI to verify this / prevent it in the future?

See this PostgREST CI failure: https://pipelines.actions.githubusercontent.com/serviceHosts/996fe3a3-010d-4e7c-a003-8e967bc4327c/_apis/pipelines/1/runs/2550/signedlogcontent/2?urlExpires=2022-08-30T06%3A30%3A28.3317426Z&urlSigningMethod=HMACV1&urlSignature=hCE13v%2Fp7jkakftXs%2FRp%2FY1EkmZVfgiucJpcj1kcobA%3D

2022-08-30T00:12:23.7448486Z �[0mhasql-pool                   > �[;1mlibrary\Hasql\Pool.hs:82:31: �[;1m�[31merror:�[0m�[0m�[;1m�[0m�[0m�[;1m�[0m
2022-08-30T00:12:23.7613309Z �[0mhasql-pool                   >     Ambiguous occurrence `Close'�[0m
2022-08-30T00:12:23.7625695Z �[0mhasql-pool                   >     It could refer to�[0m
2022-08-30T00:12:23.7647920Z �[0mhasql-pool                   >        either `Hasql.Pool.Prelude.Close',�[0m
2022-08-30T00:12:23.7650835Z �[0mhasql-pool                   >               imported from `Hasql.Pool.Prelude' at library\Hasql\Pool.hs:16:1-25�[0m
2022-08-30T00:12:23.7653713Z �[0mhasql-pool                   >               (and originally defined in `GHC.Event.Windows.ConsoleEvent')�[0m
2022-08-30T00:12:23.7655989Z �[0mhasql-pool                   >            or `Hasql.Pool.Close', defined at library\Hasql\Pool.hs:20:31�[0m�[0m�[0m
2022-08-30T00:12:23.7660646Z �[0mhasql-pool                   > �[;1m�[34m   |�[0m�[0m�[0m
2022-08-30T00:12:23.7674845Z �[0mhasql-pool                   > �[;1m�[34m82 |�[0m�[0m     writeTVar prevReuseToggle �[;1m�[31mClose�[0m�[0m�[0m
2022-08-30T00:12:23.7675918Z �[0mhasql-pool                   > �[;1m�[34m   |�[0m�[0m�[;1m�[31m                               ^^^^^�[0m�[0m

[nikita-volkov]

should Windows be added to CI to verify this / prevent it in the future?

Sure! Let's do that.

Regarding the constructor conflict, I suggest to do one of the following:

1. Hide Close on the import of Hasql.Pool.Prelude
2. Rename constructors according to a convention of appending the type name to each constructor name. Notice that the other sum types in this package do follow that convention. See the UsageError type.
3. Simply use Boolean.

I think, the second option is better, since it makes the codebase more consistent. Also the third option seems fine too.

[robx]

I went with the Bool option now for simplicity (naming things is hard), and gave up on Windows CI for now, filed the failed attempt over at #21.