Remove component-sticky package

[rfultz]

Summary

What we're after:
I'd like to remove the component-sticky package.

• It hasn't been updated in five years (npm, github)
• CSS can now do it natively (caniuse: position: sticky, :has())
• It's what GitHub uses for things like filename headers during PR reviews
• Removing more code!

Related issues

None

Completion criteria

• The component-sticky package has been removed
• Functionality has not changed

Tech steps or considerations (optional)

To test the idea and approach

A. Inspector

1. load a page with a sticky nav (left nav)
2. open Inspector
3. turn off JavaScript
4. paste :has(> .js-sticky-side) { position: sticky; top: 0px; }
5. test the page
6. (turn JavaScript back on when you're done)

B. Build process

1. from init.js and data-init.js, comment out the new Sticky lines
2. paste :has(> .js-sticky-side) { position: sticky; top: 0px; } into scss somewhere. _nav.scss?
3. npm run build
4. load a page with a sticky side nav

C. Final code changes

1. B, but…
2. remove the entire new Sticky functionality lines
3. final scss may need media/container queries so we're only making them sticky when we want to
4. ++ using has(> .js-sticky-side) would mean we don't need to adjust other class names anywhere—we can use what we already have
5. -- keeping js-sticky-side would be inconsistent with the js- prefixing signifying JavaScript targets since this would be strictly a css approach
6. are there other things we want to be sticky under certain conditions?

Future work

Are there other things we want to be sticky under certain conditions?