[CBR-227] Remove legacy wallet layer

[edsko]

This was never used, and will never be used. That is unfortunate, but at this
point won't change, and having the legacy layer makes it more awkward to modify
the layer since we have to make modifications to a layer that is never actually
used.

Description

Linked issue

Type of change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• 🛠 New feature (non-breaking change which adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)
• 🏭 Refactoring that does not change existing functionality but does improve things like code readability, structure etc
• 🔨 New or improved tests for existing code
• ⛑ git-flow chore (backport, hotfix, etc)

Developer checklist

• I have read the style guide document, and my code follows the code style of this project.
• If my code deals with exceptions, it follows the guidelines.
• I have updated any documentation accordingly, if needed. Documentation changes can be reflected in opening a PR on cardanodocs.com, amending the inline Haddock comments, any relevant README file or one of the document listed in the docs directory.
• CHANGELOG entry has been added and is linked to the correct PR on GitHub.

Testing checklist

• I have added tests to cover my changes.
• All new and existing tests passed.

QA Steps

Screenshots (if available)

[KtorZ]

Assuming that there are no changes from WalletLayer/Types.hs -> WalletLayer.hs beside the bracket functions that have been moved, LGTM 👍

[edsko]

Nope, there aren't :) Thanks!