GS-84: Pivot Table loading state

[coldrunKacper]

• Adding cache building progress bar.
• Adding Entity data loading progress bar.
• Hiding Pivot Table filters, configuration UI and Pivot Table if cache is not built.

(for the gif above I changed ROWS_API_LIMIT to 10 and ROWS_RETURN_LIMIT to 100 to be able to show the progress bar - I have only few hundreds of Activities so with standard numbers the progress bar wouldn't be visible for more than a single API call).