Indicator severity mapping (#1194)
Indicator severity mapping (#1194)

> Related #https://github.com/advthreat/iroh/issues/6176

While investigating errors on bundle import I discovered that the `severity` field of indicator was never indexed.
This PR add `severity` to indicator and expose it for searching and aggregating.
threatgrid/ctia,threatgrid/ctia,threatgrid/ctia,yogsototh/ctia,yogsototh/ctia,yogsototh/ctia,threatgrid/ctia