Added a helper script for bumping the executable spec repo

[Soupstraw]

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Description

This PR adds a script that builds the executable script Haskell library and copies all the files to the cardano-ledger-executable-spec repo. This will partially automate the bumping the executable spec for conformance testing.

Checklist

• [ ] Commit sequence broadly makes sense and commits have useful messages
• [ ] Code is formatted according to CONTRIBUTING.md
• [ ] Self-reviewed the diff

[WhatisRT]

Ah, I've already done this, see the haskell-package branch/bottom of .github/workflows/build.yml. But maybe your script is prettier than what I've done.

[WhatisRT]

Ok, then we'll have some duplicate scripts for now, but maybe it's fine.