Store provided aliases as data instead of strings

[teodorlu]

Please answer the following questions and leave the below in as part of your PR.

• [x] This PR corresponds to an issue with a clear problem statement.

  • This PR completes planned follow-up work from https://github.com/babashka/neil/issues/215

• [x] I have updated the CHANGELOG.md file with a description of the addressed issue.

  • Changelog entry already includes an entry for https://github.com/babashka/neil/issues/215

• [x] I have considered whether I should add more tests covering the code I've changed.

  • Tests have been updated to reflect new behavior

Problem: storing strings and converting to Clojure data is unncessary

Proposed solution: just store EDN

Effects:

• We can return Clojure data for aliases such as neil/kaocha-alias
• We don't need to convert from strings to Clojure data in our implementation

PR completion status

I think what I've got now is good. But I'd like to look into add-build, I think some code can be deleted.

[borkdude]

LGTM! Feel free to ping me whenever you resolved the other minor things.

[borkdude]

Ready to merge?

[teodorlu]

Yes, let's go!