Add scrollBy method to Element

[OlaviSau]

Is your feature request related to a problem? Please describe.
Our components us the scrollBy functionality and it would be great if this would be implemented as it is very simple to implement.

Describe the solution you'd like
It should be as simple as adding this to nodes/element/Element.js

	scrollBy(xCoordOrOptions, yCoord) {
		if (typeof xCoordOrOptions !== "object" && arguments.length === 1) {
			throw new TypeError(
				"Failed to execute 'scrollBy' on 'Element': The provided value is not of type 'ScrollToOptions'."
			);
		}
		const options = typeof xCoordOrOptions === "object" ? xCoordOrOptions : { left: xCoordOrOptions, top: yCoord };
		this.scroll({
			left: this.scrollLeft + (options.left ?? 0),
			top: this.scrollTop + (options.top ?? 0),
			behavior: options.behavior
		});
	}

Describe alternatives you've considered
This is part of the browser API.

Will create a PR.

[OlaviSau]

@capricorn86