Entity Sign: Improve Firefox visibility and add focus support. (#20733)

* Chenged right and left position of the infobox.

* Added focus support to open the modal.

* Moved tabindex out the constructor and added support for enter and space keys.

Author: engijlr

src/Umbraco.Web.UI.Client/src/packages/core/entity-sign/components/entity-sign-bundle.element.ts

@@ -170,9 +170,9 @@ export class UmbEntitySignBundleElement extends UmbLitElement {
 
 			.infobox {
 				position: absolute;
-				top: 100%;
+				top: 0;
 				margin-top: calc(-12px + var(--offset-h));
-				left: 100%;
+				left: 19px;
 				margin-left: -6px;
 				background-color: transparent;
 				padding: var(--uui-size-2);