Use `DuplicateRecordFields`, `NoFieldSelectors`, and `OverloadedRecordDot`

[jorisdral]

In the Haskell Unfolder episode on records, a strong case is made for using the language exensions DuplicateRecordFields, NoFieldSelectors, and OverloadedRecordDot. We use record syntax quite a bit in this repository, and we can make all that syntax more succinct by enabling these language extensions globally.

[jorisdral]

Note that I think we should only use these language extensions internally for now to make that code more succinct, so not changing the public API. If anyone decides to take on this issue, it is probably preferable to try out these language extensions in a few modules first, getting some feedback on it, and only then applying changes throughout the whole codebase