Tooltips flags

[JT-39]

Pull request overview

Several small UI and back-end improvements added to the app.

Pull request checklist

Please check if your PR fulfills the following:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Tests have been run locally and are passing (shinytest2::test_app())
• Code is styled according to tidyverse styling (checked locally with styler::style_dir() and lintr::lint_dir())

What is the current behaviour?

No errors, just a number of small improvements added to the app.

What is the new behaviour?

Here is a list of improvements made:

• Tooltips added for the Trend and Rank (Rank still needs confirming)
• Clearer and accurate Quartile Bands
• Fixed colour error in Trend (no change appearing as red)
• Adding spinners to tables and charts
• Notification pointing to GitHub for full dataset on the Create Own page
• Updated BDS and added a .csv version to repo for users to download
• Changed user created NAs in Create Your Own table to ""
• Quartile Band text colour is now white (for those coloured)
• Adding COVID flags in plots
• Fixed issue in staging table where if user created NAs in the initial query this wouldn't show.

Anything else

Maybe look into adding the COVID flag into the chart tooltips (currently showing as NA).