Use (CompactForm Coin) in IncrementalStake, DRepDistr (and other places) instead of Coin

[TimSheard]

Changed the IncrementallStake 'credMap' field to (Map (Credential 'Staking c) (CompactForm Coin))
This facilitated changing it in DRepDistr and RatifyEnv as well, Now taking a snapshot of one of these is a simple pointer copy.

Description

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated
• When applicable, versions are updated in .cabal and CHANGELOG.md files according to the
  versioning process.
• The version bounds in .cabal files for all affected packages are updated. If you change the bounds in a cabal file, that package itself must have a version increase. (See RELEASING.md)
• All visible changes are prepended to the latest section of a CHANGELOG.md for the affected packages. New section is never added with the code changes. (See RELEASING.md)
• Code is formatted with fourmolu (use scripts/fourmolize.sh)
• Cabal files are formatted (use scripts/cabal-format.sh)
• hie.yaml has been updated (use scripts/gen-hie.sh)
• Self-reviewed the diff

[lehins]

Looks great.

[TimSheard]

Using (CompactForm Coin) everywhere turns out to be a great idea. The compactCoinTxOutL makes it possible

[lehins]

Perfect! Thank you!