Advanced analytics

[QuiiBz]

We should provide advanced analytics for paying organizations, in a new tab on the Function page.

Currently, we provide the following statistics:

• Requests (includes both isolate and assets requests)
• Average CPU time
• Bytes IN/OUT

Advanced analytics should have:

• Per-region filter
• Isolate/Assets request filter
• Percentile CPU time
• Custom timeframe (could be backported to normal analytics)