chore: add Typescript support

Fixed: twpowertools:198
Change-Id: I00a14ab8ad93e9ff8d2a4d2e33824a9290500a8a
diff --git a/src/common/actionApi.js b/src/common/actionApi.js
index 0cf8528..dc22691 100644
--- a/src/common/actionApi.js
+++ b/src/common/actionApi.js
@@ -1,5 +1,9 @@
+let actionApi;
+
 // #!if browser_target == 'chromium_mv3'
-export default typeof chrome !== 'undefined' ? chrome.action : undefined;
+actionApi = typeof chrome !== 'undefined' ? chrome.action : undefined;
 // #!else
-export default typeof chrome !== 'undefined' ? chrome.browserAction : undefined;
+actionApi = typeof chrome !== 'undefined' ? chrome.browserAction : undefined;
 // #!endif
+
+export default actionApi;