Add MongoDB indices for analysis fields

[JSCU-CNI]

This PR adds keyword indices for certain fields in the analysis collection. This massively improves load time when accessing an individual analysis result in CAPE on large MongoDB instances.

CAPE uses one large OR-query when loading an analysis result which is why we opted for a separate index for every field on which the aggregation is run. The query also looks for exact matches so the fields are indexed as keyword instead of text.

[nbargnesi]

This will take a very long time for a lot of CAPE installations - terabyte scale is common. Probably better to do this in the utils somewhere and emit a warning if the indices aren't found.

[JSCU-CNI]

Where exactly do you suggest we should put this?

[nbargnesi]

I'd suggest as a new module in utils, mongodb_indices or something appropriately named.

In the startup module you can check the indices are there and emit a warning if they're missing.

Note too, the difference between doing it in startup and utils. Putting it in utils means we can add indices out-of-band, while CAPE continutes to run. Great way of making things faster incrementally without bringing CAPE down by touching startup.