Read from App Config to configure HomepageTimer (#2673)

* Read from Config for timezone timers

* Remove recusrive dependency on backstage/core and fix tsc errors

* Modify to use ConfigArray instead of fixed Config

* Fix lint and tsc errors

* Cean up app-config.yaml

* add back newline

* Fix prettier error on app-config.yaml

* Address review comments

app-config.yaml

@@ -255,3 +255,13 @@ costInsights:
       name: Your Company's Daily Cost
     DAU:
       name: Cost Per DAU
+homepage:
+  clocks:
+    - label: UTC
+      timzone: UTC
+    - label: NYC
+      timezone: 'America/New_York'
+    - label: STO
+      timezone: 'Europe/Stockholm'
+    - label: TYO
+      timezone: 'Asia/Tokyo'