(draft) refactor: use macros for WordCount

[reez]

Description

Migrate WordCount to use proc macro

Notes to the reviewers

Unfortunately lib.rs required type alias thing, but this is the same pattern used for KeychainKind in types.rs. The type alias is necessary because we can't have both an import and an enum definition with the same name in the same scope.

Changelog notice

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I've added tests for the new feature
• I've added docs for the new feature

Bugfixes:

• This pull request breaks the existing API
• I've added tests to reproduce the issue which are now passing
• I'm linking the issue being fixed by this PR