Visualisation of missing data on time series plot

[rtesra]

Aggregate with NAs and have some indicator (grey dot) that aggregate value is

Code changes required in naomi:

• [x] Refactor data aggregation scripts to aggregate with NAS
• [x] Add column to flag aggregates containing NAs

Front end changes:

• [ ] Colour dots by missing/ non missing
• [ ] Include tooltip for which area_ids are missing