Add line dash option to Overlay class

[pmatsson]

This Pull Request introduces a new feature to the Overlay class - the ability to draw shapes with dashed lines. This enhancement provides additional flexibility in the visual representation of shapes.

Please review the changes and provide any feedback. Thank you.

[bmatthieu3]

This is a great contribution and simple to add too. Thank you. I have a few remarks:

• Could you add a little documentation as well with the possible values of lineDash
• I would also add a similar options for Catalog since they can have footprints associated.

[ManonMarchand]

This feature would be nice for the support of regions visuals in cds-astro/ipyaladin#88
@bmatthieu3 is there something blocking the merge?

[bmatthieu3]

@ManonMarchand - Not that much, just some doc API that I will do

[bmatthieu3]

@pmatsson - Thanks, I fixed a little thing: when finishing drawing an overlay with a dash line, if there are other things to draw after, it would have drawn them dashed too.