Add FromField and ToField instance for Data.UUID

[mkoppmann]

The implementation is based on postgresql-simple(FromField, ToField). uuid-types is used because it contains fewer transitive dependencies, but uuid is used as a dependency for the test case.

This fixes #62.

[kmicklas]

I'm somewhat concerned with this instance since it isn't really canonical. I've used orphan instances for UUID, except encoding to binary blobs instead of text for compactness, for example.

[mkoppmann]

You’re right. That’s why I just copied what postgresql-simple did just to be consistent at least.
If this PR isn’t going to be merged, I will accept that of course and just continue to provide my own newtype wrapper in my codebase :)

[kmicklas]

What do you mean by consistent? Postgres has a native UUID type so it doesn't have to a make a choice between string/blob.

[mkoppmann]

Oh, true. I now see the problem with this too. So either we choose a default instance and people who want a binary implementation have to use a newtype, or we don’t define an instance at all.

[emberdart]

Although it's less space-saving, I suspect that the text encoding is viewed as making more sense because it can be directly queried in a textual manner.

[malteneuss]

Same as in #62:
As there are basically two valuable encodings (as binary BLOB for performance, and TEXT for human readability in e.g. CLI), would it be possible to add both encodings with BLOB as the default to be fast by default like Postgres and popular Rust libraries like rusqlite do, and a newtype wrapper like TextUUID for textual representations?

Having UUIDv7 soon in haskell-hvr/uuid#87 makes the UUID type even more appealing in databases so that out-of-the-box support would be great.