Merge #3009

3009: stylish-haskell formatting the module header r=nfrisby a=EncodePanda

Fixes IntersectMBO/ouroboros-network#2969


Not all files were following the Style Guide. The first commit fixes that. Export lists sorted alphabetically in their own respective groups, opening bracket on the same line as the module name, each export on its own new line.

The second commit adds the automatic formating of module headers.
Please note that module_header is a feature on stylish-haskell
available since 0.12.1.0 BUT it is missing a crucial configuration
aspect: open_bracket, which was recently added to stylish-haskell but
not yet released (it should be shipped with 0.12.3.0 release).
Until 0.12.3.0 is not released we must use the custom version.

Co-authored-by: EncodePanda <[email protected]>

Author: iohk-bors[bot]