feat: Adds support for line dash styles in cartesian charts

[pan-kot]

Description

The update enhances line-like cartesian chart series with dash-style support. We support all dash styles available in highcharts, but the indicators that we use in the legend and tooltip are currently on the simplistic side and only support the dashed variant. We can extend them later to support the dot or dash-dot patterns, as well as supporting the combination of area+dash.

Rel: AWSUI-61252

How has this been tested?

• New test page (covered with visual tests)

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.