Benjind/schema compare add aria label (#6767)

* Adds button extension for explicitly setting aria-label, in case the label is not screen-reader friendly

* Explicitly set aria-label for ellipsis buttons in SchemaCompare

* Changing localize call to double-quotes

* Removes unused getter for ariaLabel

src/sql/azdata.d.ts

@@ -3356,6 +3356,7 @@ declare module 'azdata' {
 		isFile?: boolean;
 		fileContent?: string;
 		title?: string;
+		ariaLabel?: string;
 	}
 
 	export interface LoadingComponentProperties {