feat(dgeni): automatically generate API doc links for code span in markdown

[griest024]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/graycoreio/daffodil/blob/develop/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Fixes: #2474

What is the new behavior?

Code spans in markdown files that match an API symbols will get automatically wrapped in an anchor pointing to the API doc page.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

There's an important gotcha here. There's not a good way to check if the code span is already wrapped in a link so any code span that links to package guides with a code span will be double wrapped. For that reason, guide links should not use code spans. e.g.
incorrect:

[`@daffodil/cart`](/libs/cart/README)

correct:

[@daffodil/cart](/libs/cart/README)