refactor(ui5-illustrated-message): rename IllustrationMessageSize enum

[dobrinyonkov]

As follow up of #8605 the enumeration of the design property is renamed to IllustrationMessageDesign

Additionally, since tags are adjusted to 2.0.0

BREAKING CHANGE: The enum IllustrationMessageSize is renamed to IllustrationMessageDesign.
If you have previously imported the enum:

import IllustrationMessageSize from "@ui5/webcomponents-base/dist/types/IllustrationMessageSize.js";

Now import IllustrationMessageDesign instead:

import IllustrationMessageDesign from "@ui5/webcomponents-base/dist/types/IllustrationMessageDesign.js";

Related to #8461, #7887