Added method to compute over-the-wire CBOR encoded transaction size

[crocodile-dentist]

Description

A method for computing the true size of cbor encoded transactions is proposed which is useful and convenient for the upcoming changes to the diffusion layer.

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]

Integer overflows is one of the leading causes of vulnerabilities. We should do our absolute best in preventing or guarding against overflows, even if they seem impossible, hence are my suggestions.

Other than that it looks good.

[lehins]

Looks great. Thank you. Couple of minor issues with changelogs. In case you are curious to learn our release and versioning process for the future you can find it here: https://github.com/IntersectMBO/cardano-ledger/blob/master/RELEASING.md

[lehins]

We are currently having an issue with CI, somehow started running out of disk space, so don't worry about we are working on it.