Update NCIDS Modal to Handle ShadowDOM Initialization

[dlescarbeau]

Issue description

We need the modal to be flexible in that it should be able to be added to either the document OR an element of our choosing (like the shadowDOM)

What's the expected change?

• The modal wrapper should be able to be added to a shadowDOM element or any element we wish. Specifically functions like the contructor and updateDialog need to be updated to handle being passed an element to append the modal to. This will have to be tested thoroughly as the expectation is still that the modal wrapper / overlay takes up the entire screen.

What's the current functionality?

• Currently the modal wrapper is always appended to the document.

Related Tickets

CIS Slider Ticket

[andyvanavery31]

Ensure this is reviewed by Analytics so that the events still work after the update. @davisaw @dlescarbeau