static attribute added to mapml-viewer

[Jacky0299]

new attribute!

closes #749.

[AliyanH]

Looks pretty good so far @Jacky0299! Seems to function nicely for all devices. I think disabling the zoom buttons was the right approach as users can always use the controlslist attribute to remove them if they wanted.
The map is still not fully 'static', for example clicking on a feature at the corner of the map, still pans the map to make the popup visible, but I don't thing this is a big issue:

Similarly, users can also zoom to a layer (right click layer -> Zoom to Layer) to pan the map, though this can be controlled by the author as they can remove the layer control using the controlslist attribute.

[AliyanH]

Just some minor styling and test changes (make the same changes to mapml-viewer and web-map). You will need to make changes to the documentation also, you can link the web-map-doc PR to this PR when done. Good work on this!

[AliyanH]

LGTM!

[prushforth]

Really good work, @Jacky0299! Thank you. Squash and merge when ready!

[prushforth]

Don't forget to do a

"git pull upstream main" on your main local branch once you have merged upstream.