Add linter and doctests to CI

[ReubenJ]

Include a run of Documenter in each package to check for proper cross-references in docstrings

• [x] https://github.com/Herb-AI/HerbCore.jl/pull/15
• [ ] https://github.com/Herb-AI/HerbConstraints.jl/pull/63
• [ ] https://github.com/Herb-AI/HerbInterpret.jl/pull/30
• [ ] https://github.com/Herb-AI/HerbGrammar.jl/pull/87
• [ ] https://github.com/Herb-AI/HerbSearch.jl/pull/117
• [ ] https://github.com/Herb-AI/HerbSpecification.jl/pull/8

[ReubenJ]

Converting existing PRs to Drafts, trying to apply BestieTemplate.jl instead, as this will result in less code for us to maintain in the future.