feat: support shadow dom elements

[driskull]

• Applies patch from Support: Web components with shadow dom #15 to support shadow DOM custom elements (web components)

[atlassian-cla-bot]

Thank you for your submission! Like many open source projects, we ask that you sign our CLA (Contributor License Agreement) before we can accept your contribution.
If your email is listed below, please ensure that you sign the CLA with the same email address.

The following users still need to sign our CLA:
❌driskull

_{Already signed the CLA? To re-check, try refreshing the page.}

[chee]

i am interested in this

[AsaAyers]

I'm using lit to make web components for a Miro sidebar. I think I need this patch to fix dragging. I'm not using this library directly, so IDK if there is a good way for me to be able to patch it. It seems like some of this code is for the target side. I can't change the code running on the main Miro board, just in my iframes.