Enable dartdoc link to source

[abitofevrything]

Description

Enables the linkToSource dartdoc option which adds a button to jump to the source definition in the generated API documentation. This makes it easier for new contributors to find types in the library, and shortens the time spent looking for API elements for regular developers.

Also corrects some invalid documentation references.

Checklist:

• Ran dart analyze or make analyze and fixed all issues
• Ran dart format --set-exit-if-changed -l 160 ./lib or make format and fixed all issues
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works