Interim historic data (#47)

* Add historic tab to interim

* Use combined dataframe for graphs

* Fix bug with engaged user calculation

* Fix double hovertext on historic engaged users graph

* Rearrange live data metrics

* Update config.toml to revert to old font.

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Co-authored-by: Kieran Pritchard <kieran.pritchard@ons.gov.uk>

Author: smstone0

.streamlit/config.toml

@@ -3,5 +3,4 @@
 primaryColor="#296398"
 backgroundColor="#ffffff"
 secondaryBackgroundColor="#e9eff5"
-textColor="#000000"
-font="sans serif"
+textColor="#000000"