Add support for multiple comparison series to LineChart

[envex]

What does this implement/fix?

As part of the ongoing tooltip work we want to allow charts to display multiple comparison lines.

These lines should be hidden until the matching series line is focused. If a chart only has a single comparison series, it show both the series and comparison series.

Does this close any currently open issues?

Resolves https://github.com/Shopify/core-issues/issues/84724

What do the changes look like?

multi-series.mov

Storybook link

Before merging

• Check your changes on a variety of browsers and devices.

• Update the Changelog's Unreleased section with your changes.

• Update relevant documentation, tests, and Storybook.

• Make sure you're exporting any new shared Components, Types and Utilities from the top level index file of the package

[github-actions]

size-limit report 📦

Path	Size	Loading time (3g)	Running time (snapdragon)	Total time
polaris-viz-core-cjs	61.64 KB (+0.19% 🔺)	1.3 s (+0.19% 🔺)	1.3 s (+2.07% 🔺)	2.5 s
polaris-viz-cjs	230.77 KB (+0.24% 🔺)	4.7 s (+0.24% 🔺)	1.6 s (-28.59% 🔽)	6.2 s
polaris-viz-esm	186.66 KB (+0.21% 🔺)	3.8 s (+0.21% 🔺)	1.7 s (+20.99% 🔺)	5.5 s
polaris-viz-css	5.86 KB (0%)	118 ms (0%)	299 ms (-22.69% 🔽)	417 ms
polaris-viz-esnext	193.98 KB (+0.27% 🔺)	3.9 s (+0.27% 🔺)	1.5 s (+17.34% 🔺)	5.4 s