[FEATURE]: Enable dashed legend markers for shape traces

[camdecoster]

Description

Enable dashed legend markers for shape traces.

Why should this feature be added?

This will complete the feature that was originally added in #7673.

Notes

• This was carved out of Add support for dashed marker lines in scatter plots #7673 because it's technically a breaking change
• Check that PR to see where changes will need to be made to enable this feature