Merged PR 194909: Add report getTheme API

[WIP]

Author: aliabufoul

dist/powerbi-client.d.ts

@@ -1368,6 +1368,14 @@ declare module "report" {
          * ```
          */
         resetTheme(): Promise<void>;
+        /**
+         * get the theme of the report
+         *
+         * ```javascript
+         * report.getTheme();
+         * ```
+         */
+        getTheme(): Promise<IReportTheme>;
         /**
          * Reset user's filters, slicers, and other data view changes to the default state of the report
          *