Bump haddock version to 2.30.0 and restore missing commits from various branches

Restore missing haddock commits from various branches including:

• The commit from the ghc-9.10 branch: https://gitlab.haskell.org/ghc/haddock/-/tree/1432bcc943d41736eca491ecec4eb9a6304dab36
• https://github.com/haskell/haddock/tree/main
• https://gitlab.haskell.org/ghc/haddock
• Bump version to 2.30.0 as this is the version in the GHC-9.8 branch and the newest version in any branch