Prepare for package registration

[MillironX]

Types of changes

This PR implements the following changes:

• ✨ New feature (A non-breaking change which adds functionality).
• 🐛 Bug fix (A non-breaking change, which fixes an issue).
• 💥 Breaking change (fix or feature that would cause existing functionality to change).

📋 Additional detail

This PR adds metadata and workflow information to prepare SequenceVariation for registration in the general registry. Specific additions:

• GitHub actions workflows
  • CompatHelper
  • Documenter
  • TagBot
  • CI/Unit testing
  • @JuliaRegistrator
• GitHub issue/pull request templates
• Documentation
• gitignore for Manifest.toml (and removed Manifest.toml)
• License
• Changelog
• [compat] section to Project.toml

Fixes #8

☑️ Checklist

• 🎨 The changes implemented is consistent with the julia style guide.
• 📘 I have updated and added relevant docstrings, in a manner consistent with the documentation styleguide.
• 📘 I have added or updated relevant user and developer manuals/documentation in docs/src/.
• 🆗 There are unit tests that cover the code changes I have made.
• 🆗 The unit tests cover my code changes AND they pass.
• 📝 I have added an entry to the [UNRELEASED] section of the manually curated CHANGELOG.md file for this repository.
• 🆗 All changes should be compatible with the latest stable version of Julia.
• 💭 I have commented liberally for any complex pieces of internal code.

[MillironX]

@jakobnissen I'd appreciate you looking this over to make sure everything is up to BioJulia standards. Thanks

[kescobo]

🎉

[kescobo]

Sorry for never getting to review, but it all looks great! Thanks for getting it set up.